STL algorithm源代码：stl_algo.h

<span style="font-size:18px;">// Algorithm implementation -*- C++ -*-

// Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
// 2010, 2011
// Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/*
*
* Copyright (c) 1994
* Hewlett-Packard Company
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation.  Hewlett-Packard Company makes no
* representations about the suitability of this software for any
* purpose.  It is provided "as is" without express or implied warranty.
*
*
* Copyright (c) 1996
* Silicon Graphics Computer Systems, Inc.
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation.  Silicon Graphics makes no
* representations about the suitability of this software for any
* purpose.  It is provided "as is" without express or implied warranty.
*/

/** @file bits/stl_algo.h
*  This is an internal header file, included by other library headers.
*  Do not attempt to use it directly. @headername{algorithm}
*/

#ifndef _STL_ALGO_H
#define _STL_ALGO_H 1

#include <cstdlib>             // for rand
#include <bits/algorithmfwd.h>
#include <bits/stl_heap.h>
#include <bits/stl_tempbuf.h>  // for _Temporary_buffer

#ifdef __GXX_EXPERIMENTAL_CXX0X__
#include <random>     // for std::uniform_int_distribution
#include <functional> // for std::bind
#endif

// See concept_check.h for the __glibcxx_*_requires macros.

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

/// Swaps the median value of *__a, *__b and *__c to *__a
template<typename _Iterator>
void
__move_median_first(_Iterator __a, _Iterator __b, _Iterator __c)
{
// concept requirements
__glibcxx_function_requires(_LessThanComparableConcept<
typename iterator_traits<_Iterator>::value_type>)

if (*__a < *__b)
{
if (*__b < *__c)
std::iter_swap(__a, __b);
else if (*__a < *__c)
std::iter_swap(__a, __c);
}
else if (*__a < *__c)
return;
else if (*__b < *__c)
std::iter_swap(__a, __c);
else
std::iter_swap(__a, __b);
}

/// Swaps the median value of *__a, *__b and *__c under __comp to *__a
template<typename _Iterator, typename _Compare>
void
__move_median_first(_Iterator __a, _Iterator __b, _Iterator __c,
_Compare __comp)
{
// concept requirements
__glibcxx_function_requires(_BinaryFunctionConcept<_Compare, bool,
typename iterator_traits<_Iterator>::value_type,
typename iterator_traits<_Iterator>::value_type>)

if (__comp(*__a, *__b))
{
if (__comp(*__b, *__c))
std::iter_swap(__a, __b);
else if (__comp(*__a, *__c))
std::iter_swap(__a, __c);
}
else if (__comp(*__a, *__c))
return;
else if (__comp(*__b, *__c))
std::iter_swap(__a, __c);
else
std::iter_swap(__a, __b);
}

// for_each

/// This is an overload used by find() for the Input Iterator case.
template<typename _InputIterator, typename _Tp>
inline _InputIterator
__find(_InputIterator __first, _InputIterator __last,
const _Tp& __val, input_iterator_tag)
{
while (__first != __last && !(*__first == __val))
++__first;
return __first;
}

/// This is an overload used by find_if() for the Input Iterator case.
template<typename _InputIterator, typename _Predicate>
inline _InputIterator
__find_if(_InputIterator __first, _InputIterator __last,
_Predicate __pred, input_iterator_tag)
{
while (__first != __last && !bool(__pred(*__first)))
++__first;
return __first;
}

/// This is an overload used by find() for the RAI case.
template<typename _RandomAccessIterator, typename _Tp>
_RandomAccessIterator
__find(_RandomAccessIterator __first, _RandomAccessIterator __last,
const _Tp& __val, random_access_iterator_tag)
{
typename iterator_traits<_RandomAccessIterator>::difference_type
__trip_count = (__last - __first) >> 2;

for (; __trip_count > 0; --__trip_count)
{
if (*__first == __val)
return __first;
++__first;

if (*__first == __val)
return __first;
++__first;

if (*__first == __val)
return __first;
++__first;

if (*__first == __val)
return __first;
++__first;
}

switch (__last - __first)
{
case 3:
if (*__first == __val)
return __first;
++__first;
case 2:
if (*__first == __val)
return __first;
++__first;
case 1:
if (*__first == __val)
return __first;
++__first;
case 0:
default:
return __last;
}
}

/// This is an overload used by find_if() for the RAI case.
template<typename _RandomAccessIterator, typename _Predicate>
_RandomAccessIterator
__find_if(_RandomAccessIterator __first, _RandomAccessIterator __last,
_Predicate __pred, random_access_iterator_tag)
{
typename iterator_traits<_RandomAccessIterator>::difference_type
__trip_count = (__last - __first) >> 2;

for (; __trip_count > 0; --__trip_count)
{
if (__pred(*__first))
return __first;
++__first;

if (__pred(*__first))
return __first;
++__first;

if (__pred(*__first))
return __first;
++__first;

if (__pred(*__first))
return __first;
++__first;
}

switch (__last - __first)
{
case 3:
if (__pred(*__first))
return __first;
++__first;
case 2:
if (__pred(*__first))
return __first;
++__first;
case 1:
if (__pred(*__first))
return __first;
++__first;
case 0:
default:
return __last;
}
}

/// This is an overload used by find_if_not() for the Input Iterator case.
template<typename _InputIterator, typename _Predicate>
inline _InputIterator
__find_if_not(_InputIterator __first, _InputIterator __last,
_Predicate __pred, input_iterator_tag)
{
while (__first != __last && bool(__pred(*__first)))
++__first;
return __first;
}

/// This is an overload used by find_if_not() for the RAI case.
template<typename _RandomAccessIterator, typename _Predicate>
_RandomAccessIterator
__find_if_not(_RandomAccessIterator __first, _RandomAccessIterator __last,
_Predicate __pred, random_access_iterator_tag)
{
typename iterator_traits<_RandomAccessIterator>::difference_type
__trip_count = (__last - __first) >> 2;

for (; __trip_count > 0; --__trip_count)
{
if (!bool(__pred(*__first)))
return __first;
++__first;

if (!bool(__pred(*__first)))
return __first;
++__first;

if (!bool(__pred(*__first)))
return __first;
++__first;

if (!bool(__pred(*__first)))
return __first;
++__first;
}

switch (__last - __first)
{
case 3:
if (!bool(__pred(*__first)))
return __first;
++__first;
case 2:
if (!bool(__pred(*__first)))
return __first;
++__first;
case 1:
if (!bool(__pred(*__first)))
return __first;
++__first;
case 0:
default:
return __last;
}
}

/// Provided for stable_partition to use.
template<typename _InputIterator, typename _Predicate>
inline _InputIterator
__find_if_not(_InputIterator __first, _InputIterator __last,
_Predicate __pred)
{
return std::__find_if_not(__first, __last, __pred,
std::__iterator_category(__first));
}

/// Like find_if_not(), but uses and updates a count of the
/// remaining range length instead of comparing against an end
/// iterator.
template<typename _InputIterator, typename _Predicate, typename _Distance>
_InputIterator
__find_if_not_n(_InputIterator __first, _Distance& __len, _Predicate __pred)
{
for (; __len; --__len, ++__first)
if (!bool(__pred(*__first)))
break;
return __first;
}

// set_difference
// set_intersection
// set_symmetric_difference
// set_union
// for_each
// find
// find_if
// find_first_of
// adjacent_find
// count
// count_if
// search

/**
*  This is an uglified
*  search_n(_ForwardIterator, _ForwardIterator, _Integer, const _Tp&)
*  overloaded for forward iterators.
*/
template<typename _ForwardIterator, typename _Integer, typename _Tp>
_ForwardIterator
__search_n(_ForwardIterator __first, _ForwardIterator __last,
_Integer __count, const _Tp& __val,
std::forward_iterator_tag)
{
__first = _GLIBCXX_STD_A::find(__first, __last, __val);
while (__first != __last)
{
typename iterator_traits<_ForwardIterator>::difference_type
__n = __count;
_ForwardIterator __i = __first;
++__i;
while (__i != __last && __n != 1 && *__i == __val)
{
++__i;
--__n;
}
if (__n == 1)
return __first;
if (__i == __last)
return __last;
__first = _GLIBCXX_STD_A::find(++__i, __last, __val);
}
return __last;
}

/**
*  This is an uglified
*  search_n(_ForwardIterator, _ForwardIterator, _Integer, const _Tp&)
*  overloaded for random access iterators.
*/
template<typename _RandomAccessIter, typename _Integer, typename _Tp>
_RandomAccessIter
__search_n(_RandomAccessIter __first, _RandomAccessIter __last,
_Integer __count, const _Tp& __val,
std::random_access_iterator_tag)
{

typedef typename std::iterator_traits<_RandomAccessIter>::difference_type
_DistanceType;

_DistanceType __tailSize = __last - __first;
const _DistanceType __pattSize = __count;

if (__tailSize < __pattSize)
return __last;

const _DistanceType __skipOffset = __pattSize - 1;
_RandomAccessIter __lookAhead = __first + __skipOffset;
__tailSize -= __pattSize;

while (1) // the main loop...
{
// __lookAhead here is always pointing to the last element of next
// possible match.
while (!(*__lookAhead == __val)) // the skip loop...
{
if (__tailSize < __pattSize)
return __last;  // Failure
__lookAhead += __pattSize;
__tailSize -= __pattSize;
}
_DistanceType __remainder = __skipOffset;
for (_RandomAccessIter __backTrack = __lookAhead - 1;
*__backTrack == __val; --__backTrack)
{
if (--__remainder == 0)
return (__lookAhead - __skipOffset); // Success
}
if (__remainder > __tailSize)
return __last; // Failure
__lookAhead += __remainder;
__tailSize -= __remainder;
}
}

// search_n

/**
*  This is an uglified
*  search_n(_ForwardIterator, _ForwardIterator, _Integer, const _Tp&,
*	       _BinaryPredicate)
*  overloaded for forward iterators.
*/
template<typename _ForwardIterator, typename _Integer, typename _Tp,
typename _BinaryPredicate>
_ForwardIterator
__search_n(_ForwardIterator __first, _ForwardIterator __last,
_Integer __count, const _Tp& __val,
_BinaryPredicate __binary_pred, std::forward_iterator_tag)
{
while (__first != __last && !bool(__binary_pred(*__first, __val)))
++__first;

while (__first != __last)
{
typename iterator_traits<_ForwardIterator>::difference_type
__n = __count;
_ForwardIterator __i = __first;
++__i;
while (__i != __last && __n != 1 && bool(__binary_pred(*__i, __val)))
{
++__i;
--__n;
}
if (__n == 1)
return __first;
if (__i == __last)
return __last;
__first = ++__i;
while (__first != __last
&& !bool(__binary_pred(*__first, __val)))
++__first;
}
return __last;
}

/**
*  This is an uglified
*  search_n(_ForwardIterator, _ForwardIterator, _Integer, const _Tp&,
*	       _BinaryPredicate)
*  overloaded for random access iterators.
*/
template<typename _RandomAccessIter, typename _Integer, typename _Tp,
typename _BinaryPredicate>
_RandomAccessIter
__search_n(_RandomAccessIter __first, _RandomAccessIter __last,
_Integer __count, const _Tp& __val,
_BinaryPredicate __binary_pred, std::random_access_iterator_tag)
{

typedef typename std::iterator_traits<_RandomAccessIter>::difference_type
_DistanceType;

_DistanceType __tailSize = __last - __first;
const _DistanceType __pattSize = __count;

if (__tailSize < __pattSize)
return __last;

const _DistanceType __skipOffset = __pattSize - 1;
_RandomAccessIter __lookAhead = __first + __skipOffset;
__tailSize -= __pattSize;

while (1) // the main loop...
{
// __lookAhead here is always pointing to the last element of next
// possible match.
while (!bool(__binary_pred(*__lookAhead, __val))) // the skip loop...
{
if (__tailSize < __pattSize)
return __last;  // Failure
__lookAhead += __pattSize;
__tailSize -= __pattSize;
}
_DistanceType __remainder = __skipOffset;
for (_RandomAccessIter __backTrack = __lookAhead - 1;
__binary_pred(*__backTrack, __val); --__backTrack)
{
if (--__remainder == 0)
return (__lookAhead - __skipOffset); // Success
}
if (__remainder > __tailSize)
return __last; // Failure
__lookAhead += __remainder;
__tailSize -= __remainder;
}
}

// find_end for forward iterators.
template<typename _ForwardIterator1, typename _ForwardIterator2>
_ForwardIterator1
__find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
_ForwardIterator2 __first2, _ForwardIterator2 __last2,
forward_iterator_tag, forward_iterator_tag)
{
if (__first2 == __last2)
return __last1;
else
{
_ForwardIterator1 __result = __last1;
while (1)
{
_ForwardIterator1 __new_result
= _GLIBCXX_STD_A::search(__first1, __last1, __first2, __last2);
if (__new_result == __last1)
return __result;
else
{
__result = __new_result;
__first1 = __new_result;
++__first1;
}
}
}
}

template<typename _ForwardIterator1, typename _ForwardIterator2,
typename _BinaryPredicate>
_ForwardIterator1
__find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
_ForwardIterator2 __first2, _ForwardIterator2 __last2,
forward_iterator_tag, forward_iterator_tag,
_BinaryPredicate __comp)
{
if (__first2 == __last2)
return __last1;
else
{
_ForwardIterator1 __result = __last1;
while (1)
{
_ForwardIterator1 __new_result
= _GLIBCXX_STD_A::search(__first1, __last1, __first2,
__last2, __comp);
if (__new_result == __last1)
return __result;
else
{
__result = __new_result;
__first1 = __new_result;
++__first1;
}
}
}
}

// find_end for bidirectional iterators (much faster).
template<typename _BidirectionalIterator1, typename _BidirectionalIterator2>
_BidirectionalIterator1
__find_end(_BidirectionalIterator1 __first1,
_BidirectionalIterator1 __last1,
_BidirectionalIterator2 __first2,
_BidirectionalIterator2 __last2,
bidirectional_iterator_tag, bidirectional_iterator_tag)
{
// concept requirements
__glibcxx_function_requires(_BidirectionalIteratorConcept<
_BidirectionalIterator1>)
__glibcxx_function_requires(_BidirectionalIteratorConcept<
_BidirectionalIterator2>)

typedef reverse_iterator<_BidirectionalIterator1> _RevIterator1;
typedef reverse_iterator<_BidirectionalIterator2> _RevIterator2;

_RevIterator1 __rlast1(__first1);
_RevIterator2 __rlast2(__first2);
_RevIterator1 __rresult = _GLIBCXX_STD_A::search(_RevIterator1(__last1),
__rlast1,
_RevIterator2(__last2),
__rlast2);

if (__rresult == __rlast1)
return __last1;
else
{
_BidirectionalIterator1 __result = __rresult.base();
std::advance(__result, -std::distance(__first2, __last2));
return __result;
}
}

template<typename _BidirectionalIterator1, typename _BidirectionalIterator2,
typename _BinaryPredicate>
_BidirectionalIterator1
__find_end(_BidirectionalIterator1 __first1,
_BidirectionalIterator1 __last1,
_BidirectionalIterator2 __first2,
_BidirectionalIterator2 __last2,
bidirectional_iterator_tag, bidirectional_iterator_tag,
_BinaryPredicate __comp)
{
// concept requirements
__glibcxx_function_requires(_BidirectionalIteratorConcept<
_BidirectionalIterator1>)
__glibcxx_function_requires(_BidirectionalIteratorConcept<
_BidirectionalIterator2>)

typedef reverse_iterator<_BidirectionalIterator1> _RevIterator1;
typedef reverse_iterator<_BidirectionalIterator2> _RevIterator2;

_RevIterator1 __rlast1(__first1);
_RevIterator2 __rlast2(__first2);
_RevIterator1 __rresult = std::search(_RevIterator1(__last1), __rlast1,
_RevIterator2(__last2), __rlast2,
__comp);

if (__rresult == __rlast1)
return __last1;
else
{
_BidirectionalIterator1 __result = __rresult.base();
std::advance(__result, -std::distance(__first2, __last2));
return __result;
}
}

/**
*  @brief  Find last matching subsequence in a sequence.
*  @ingroup non_mutating_algorithms
*  @param  __first1  Start of range to search.
*  @param  __last1   End of range to search.
*  @param  __first2  Start of sequence to match.
*  @param  __last2   End of sequence to match.
*  @return   The last iterator @c i in the range
*  @p [__first1,__last1-(__last2-__first2)) such that @c *(i+N) ==
*  @p *(__first2+N) for each @c N in the range @p
*  [0,__last2-__first2), or @p __last1 if no such iterator exists.
*
*  Searches the range @p [__first1,__last1) for a sub-sequence that
*  compares equal value-by-value with the sequence given by @p
*  [__first2,__last2) and returns an iterator to the __first
*  element of the sub-sequence, or @p __last1 if the sub-sequence
*  is not found.  The sub-sequence will be the last such
*  subsequence contained in [__first,__last1).
*
*  Because the sub-sequence must lie completely within the range @p
*  [__first1,__last1) it must start at a position less than @p
*  __last1-(__last2-__first2) where @p __last2-__first2 is the
*  length of the sub-sequence.  This means that the returned
*  iterator @c i will be in the range @p
*  [__first1,__last1-(__last2-__first2))
*/
template<typename _ForwardIterator1, typename _ForwardIterator2>
inline _ForwardIterator1
find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
_ForwardIterator2 __first2, _ForwardIterator2 __last2)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)
__glibcxx_function_requires(_EqualOpConcept<
typename iterator_traits<_ForwardIterator1>::value_type,
typename iterator_traits<_ForwardIterator2>::value_type>)
__glibcxx_requires_valid_range(__first1, __last1);
__glibcxx_requires_valid_range(__first2, __last2);

return std::__find_end(__first1, __last1, __first2, __last2,
std::__iterator_category(__first1),
std::__iterator_category(__first2));
}

/**
*  @brief  Find last matching subsequence in a sequence using a predicate.
*  @ingroup non_mutating_algorithms
*  @param  __first1  Start of range to search.
*  @param  __last1   End of range to search.
*  @param  __first2  Start of sequence to match.
*  @param  __last2   End of sequence to match.
*  @param  __comp    The predicate to use.
*  @return The last iterator @c i in the range @p
*  [__first1,__last1-(__last2-__first2)) such that @c
*  predicate(*(i+N), @p (__first2+N)) is true for each @c N in the
*  range @p [0,__last2-__first2), or @p __last1 if no such iterator
*  exists.
*
*  Searches the range @p [__first1,__last1) for a sub-sequence that
*  compares equal value-by-value with the sequence given by @p
*  [__first2,__last2) using comp as a predicate and returns an
*  iterator to the first element of the sub-sequence, or @p __last1
*  if the sub-sequence is not found.  The sub-sequence will be the
*  last such subsequence contained in [__first,__last1).
*
*  Because the sub-sequence must lie completely within the range @p
*  [__first1,__last1) it must start at a position less than @p
*  __last1-(__last2-__first2) where @p __last2-__first2 is the
*  length of the sub-sequence.  This means that the returned
*  iterator @c i will be in the range @p
*  [__first1,__last1-(__last2-__first2))
*/
template<typename _ForwardIterator1, typename _ForwardIterator2,
typename _BinaryPredicate>
inline _ForwardIterator1
find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
_ForwardIterator2 __first2, _ForwardIterator2 __last2,
_BinaryPredicate __comp)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)
__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
typename iterator_traits<_ForwardIterator1>::value_type,
typename iterator_traits<_ForwardIterator2>::value_type>)
__glibcxx_requires_valid_range(__first1, __last1);
__glibcxx_requires_valid_range(__first2, __last2);

return std::__find_end(__first1, __last1, __first2, __last2,
std::__iterator_category(__first1),
std::__iterator_category(__first2),
__comp);
}

#ifdef __GXX_EXPERIMENTAL_CXX0X__
/**
*  @brief  Checks that a predicate is true for all the elements
*          of a sequence.
*  @ingroup non_mutating_algorithms
*  @param  __first   An input iterator.
*  @param  __last    An input iterator.
*  @param  __pred    A predicate.
*  @return  True if the check is true, false otherwise.
*
*  Returns true if @p __pred is true for each element in the range
*  @p [__first,__last), and false otherwise.
*/
template<typename _InputIterator, typename _Predicate>
inline bool
all_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
{ return __last == std::find_if_not(__first, __last, __pred); }

/**
*  @brief  Checks that a predicate is false for all the elements
*          of a sequence.
*  @ingroup non_mutating_algorithms
*  @param  __first   An input iterator.
*  @param  __last    An input iterator.
*  @param  __pred    A predicate.
*  @return  True if the check is true, false otherwise.
*
*  Returns true if @p __pred is false for each element in the range
*  @p [__first,__last), and false otherwise.
*/
template<typename _InputIterator, typename _Predicate>
inline bool
none_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
{ return __last == _GLIBCXX_STD_A::find_if(__first, __last, __pred); }

/**
*  @brief  Checks that a predicate is false for at least an element
*          of a sequence.
*  @ingroup non_mutating_algorithms
*  @param  __first   An input iterator.
*  @param  __last    An input iterator.
*  @param  __pred    A predicate.
*  @return  True if the check is true, false otherwise.
*
*  Returns true if an element exists in the range @p
*  [__first,__last) such that @p __pred is true, and false
*  otherwise.
*/
template<typename _InputIterator, typename _Predicate>
inline bool
any_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
{ return !std::none_of(__first, __last, __pred); }

/**
*  @brief  Find the first element in a sequence for which a
*          predicate is false.
*  @ingroup non_mutating_algorithms
*  @param  __first  An input iterator.
*  @param  __last   An input iterator.
*  @param  __pred   A predicate.
*  @return   The first iterator @c i in the range @p [__first,__last)
*  such that @p __pred(*i) is false, or @p __last if no such iterator exists.
*/
template<typename _InputIterator, typename _Predicate>
inline _InputIterator
find_if_not(_InputIterator __first, _InputIterator __last,
_Predicate __pred)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
typename iterator_traits<_InputIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);
return std::__find_if_not(__first, __last, __pred);
}

/**
*  @brief  Checks whether the sequence is partitioned.
*  @ingroup mutating_algorithms
*  @param  __first  An input iterator.
*  @param  __last   An input iterator.
*  @param  __pred   A predicate.
*  @return  True if the range @p [__first,__last) is partioned by @p __pred,
*  i.e. if all elements that satisfy @p __pred appear before those that
*  do not.
*/
template<typename _InputIterator, typename _Predicate>
inline bool
is_partitioned(_InputIterator __first, _InputIterator __last,
_Predicate __pred)
{
__first = std::find_if_not(__first, __last, __pred);
return std::none_of(__first, __last, __pred);
}

/**
*  @brief  Find the partition point of a partitioned range.
*  @ingroup mutating_algorithms
*  @param  __first   An iterator.
*  @param  __last    Another iterator.
*  @param  __pred    A predicate.
*  @return  An iterator @p mid such that @p all_of(__first, mid, __pred)
*           and @p none_of(mid, __last, __pred) are both true.
*/
template<typename _ForwardIterator, typename _Predicate>
_ForwardIterator
partition_point(_ForwardIterator __first, _ForwardIterator __last,
_Predicate __pred)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
typename iterator_traits<_ForwardIterator>::value_type>)

// A specific debug-mode test will be necessary...
__glibcxx_requires_valid_range(__first, __last);

typedef typename iterator_traits<_ForwardIterator>::difference_type
_DistanceType;

_DistanceType __len = std::distance(__first, __last);
_DistanceType __half;
_ForwardIterator __middle;

while (__len > 0)
{
__half = __len >> 1;
__middle = __first;
std::advance(__middle, __half);
if (__pred(*__middle))
{
__first = __middle;
++__first;
__len = __len - __half - 1;
}
else
__len = __half;
}
return __first;
}
#endif

/**
*  @brief Copy a sequence, removing elements of a given value.
*  @ingroup mutating_algorithms
*  @param  __first   An input iterator.
*  @param  __last    An input iterator.
*  @param  __result  An output iterator.
*  @param  __value   The value to be removed.
*  @return   An iterator designating the end of the resulting sequence.
*
*  Copies each element in the range @p [__first,__last) not equal
*  to @p __value to the range beginning at @p __result.
*  remove_copy() is stable, so the relative order of elements that
*  are copied is unchanged.
*/
template<typename _InputIterator, typename _OutputIterator, typename _Tp>
_OutputIterator
remove_copy(_InputIterator __first, _InputIterator __last,
_OutputIterator __result, const _Tp& __value)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
typename iterator_traits<_InputIterator>::value_type>)
__glibcxx_function_requires(_EqualOpConcept<
typename iterator_traits<_InputIterator>::value_type, _Tp>)
__glibcxx_requires_valid_range(__first, __last);

for (; __first != __last; ++__first)
if (!(*__first == __value))
{
*__result = *__first;
++__result;
}
return __result;
}

/**
*  @brief Copy a sequence, removing elements for which a predicate is true.
*  @ingroup mutating_algorithms
*  @param  __first   An input iterator.
*  @param  __last    An input iterator.
*  @param  __result  An output iterator.
*  @param  __pred    A predicate.
*  @return   An iterator designating the end of the resulting sequence.
*
*  Copies each element in the range @p [__first,__last) for which
*  @p __pred returns false to the range beginning at @p __result.
*
*  remove_copy_if() is stable, so the relative order of elements that are
*  copied is unchanged.
*/
template<typename _InputIterator, typename _OutputIterator,
typename _Predicate>
_OutputIterator
remove_copy_if(_InputIterator __first, _InputIterator __last,
_OutputIterator __result, _Predicate __pred)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
typename iterator_traits<_InputIterator>::value_type>)
__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
typename iterator_traits<_InputIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

for (; __first != __last; ++__first)
if (!bool(__pred(*__first)))
{
*__result = *__first;
++__result;
}
return __result;
}

#ifdef __GXX_EXPERIMENTAL_CXX0X__
/**
*  @brief Copy the elements of a sequence for which a predicate is true.
*  @ingroup mutating_algorithms
*  @param  __first   An input iterator.
*  @param  __last    An input iterator.
*  @param  __result  An output iterator.
*  @param  __pred    A predicate.
*  @return   An iterator designating the end of the resulting sequence.
*
*  Copies each element in the range @p [__first,__last) for which
*  @p __pred returns true to the range beginning at @p __result.
*
*  copy_if() is stable, so the relative order of elements that are
*  copied is unchanged.
*/
template<typename _InputIterator, typename _OutputIterator,
typename _Predicate>
_OutputIterator
copy_if(_InputIterator __first, _InputIterator __last,
_OutputIterator __result, _Predicate __pred)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
typename iterator_traits<_InputIterator>::value_type>)
__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
typename iterator_traits<_InputIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

for (; __first != __last; ++__first)
if (__pred(*__first))
{
*__result = *__first;
++__result;
}
return __result;
}

template<typename _InputIterator, typename _Size, typename _OutputIterator>
_OutputIterator
__copy_n(_InputIterator __first, _Size __n,
_OutputIterator __result, input_iterator_tag)
{
if (__n > 0)
{
while (true)
{
*__result = *__first;
++__result;
if (--__n > 0)
++__first;
else
break;
}
}
return __result;
}

template<typename _RandomAccessIterator, typename _Size,
typename _OutputIterator>
inline _OutputIterator
__copy_n(_RandomAccessIterator __first, _Size __n,
_OutputIterator __result, random_access_iterator_tag)
{ return std::copy(__first, __first + __n, __result); }

/**
*  @brief Copies the range [first,first+n) into [result,result+n).
*  @ingroup mutating_algorithms
*  @param  __first  An input iterator.
*  @param  __n      The number of elements to copy.
*  @param  __result An output iterator.
*  @return  result+n.
*
*  This inline function will boil down to a call to @c memmove whenever
*  possible.  Failing that, if random access iterators are passed, then the
*  loop count will be known (and therefore a candidate for compiler
*  optimizations such as unrolling).
*/
template<typename _InputIterator, typename _Size, typename _OutputIterator>
inline _OutputIterator
copy_n(_InputIterator __first, _Size __n, _OutputIterator __result)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
typename iterator_traits<_InputIterator>::value_type>)

return std::__copy_n(__first, __n, __result,
std::__iterator_category(__first));
}

/**
*  @brief Copy the elements of a sequence to separate output sequences
*         depending on the truth value of a predicate.
*  @ingroup mutating_algorithms
*  @param  __first   An input iterator.
*  @param  __last    An input iterator.
*  @param  __out_true   An output iterator.
*  @param  __out_false  An output iterator.
*  @param  __pred    A predicate.
*  @return   A pair designating the ends of the resulting sequences.
*
*  Copies each element in the range @p [__first,__last) for which
*  @p __pred returns true to the range beginning at @p out_true
*  and each element for which @p __pred returns false to @p __out_false.
*/
template<typename _InputIterator, typename _OutputIterator1,
typename _OutputIterator2, typename _Predicate>
pair<_OutputIterator1, _OutputIterator2>
partition_copy(_InputIterator __first, _InputIterator __last,
_OutputIterator1 __out_true, _OutputIterator2 __out_false,
_Predicate __pred)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator1,
typename iterator_traits<_InputIterator>::value_type>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator2,
typename iterator_traits<_InputIterator>::value_type>)
__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
typename iterator_traits<_InputIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

for (; __first != __last; ++__first)
if (__pred(*__first))
{
*__out_true = *__first;
++__out_true;
}
else
{
*__out_false = *__first;
++__out_false;
}

return pair<_OutputIterator1, _OutputIterator2>(__out_true, __out_false);
}
#endif

/**
*  @brief Remove elements from a sequence.
*  @ingroup mutating_algorithms
*  @param  __first  An input iterator.
*  @param  __last   An input iterator.
*  @param  __value  The value to be removed.
*  @return   An iterator designating the end of the resulting sequence.
*
*  All elements equal to @p __value are removed from the range
*  @p [__first,__last).
*
*  remove() is stable, so the relative order of elements that are
*  not removed is unchanged.
*
*  Elements between the end of the resulting sequence and @p __last
*  are still present, but their value is unspecified.
*/
template<typename _ForwardIterator, typename _Tp>
_ForwardIterator
remove(_ForwardIterator __first, _ForwardIterator __last,
const _Tp& __value)
{
// concept requirements
__glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
_ForwardIterator>)
__glibcxx_function_requires(_EqualOpConcept<
typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
__glibcxx_requires_valid_range(__first, __last);

__first = _GLIBCXX_STD_A::find(__first, __last, __value);
if(__first == __last)
return __first;
_ForwardIterator __result = __first;
++__first;
for(; __first != __last; ++__first)
if(!(*__first == __value))
{
*__result = _GLIBCXX_MOVE(*__first);
++__result;
}
return __result;
}

/**
*  @brief Remove elements from a sequence using a predicate.
*  @ingroup mutating_algorithms
*  @param  __first  A forward iterator.
*  @param  __last   A forward iterator.
*  @param  __pred   A predicate.
*  @return   An iterator designating the end of the resulting sequence.
*
*  All elements for which @p __pred returns true are removed from the range
*  @p [__first,__last).
*
*  remove_if() is stable, so the relative order of elements that are
*  not removed is unchanged.
*
*  Elements between the end of the resulting sequence and @p __last
*  are still present, but their value is unspecified.
*/
template<typename _ForwardIterator, typename _Predicate>
_ForwardIterator
remove_if(_ForwardIterator __first, _ForwardIterator __last,
_Predicate __pred)
{
// concept requirements
__glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
_ForwardIterator>)
__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

__first = _GLIBCXX_STD_A::find_if(__first, __last, __pred);
if(__first == __last)
return __first;
_ForwardIterator __result = __first;
++__first;
for(; __first != __last; ++__first)
if(!bool(__pred(*__first)))
{
*__result = _GLIBCXX_MOVE(*__first);
++__result;
}
return __result;
}

/**
*  @brief Remove consecutive duplicate values from a sequence.
*  @ingroup mutating_algorithms
*  @param  __first  A forward iterator.
*  @param  __last   A forward iterator.
*  @return  An iterator designating the end of the resulting sequence.
*
*  Removes all but the first element from each group of consecutive
*  values that compare equal.
*  unique() is stable, so the relative order of elements that are
*  not removed is unchanged.
*  Elements between the end of the resulting sequence and @p __last
*  are still present, but their value is unspecified.
*/
template<typename _ForwardIterator>
_ForwardIterator
unique(_ForwardIterator __first, _ForwardIterator __last)
{
// concept requirements
__glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
_ForwardIterator>)
__glibcxx_function_requires(_EqualityComparableConcept<
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

// Skip the beginning, if already unique.
__first = _GLIBCXX_STD_A::adjacent_find(__first, __last);
if (__first == __last)
return __last;

// Do the real copy work.
_ForwardIterator __dest = __first;
++__first;
while (++__first != __last)
if (!(*__dest == *__first))
*++__dest = _GLIBCXX_MOVE(*__first);
return ++__dest;
}

/**
*  @brief Remove consecutive values from a sequence using a predicate.
*  @ingroup mutating_algorithms
*  @param  __first        A forward iterator.
*  @param  __last         A forward iterator.
*  @param  __binary_pred  A binary predicate.
*  @return  An iterator designating the end of the resulting sequence.
*
*  Removes all but the first element from each group of consecutive
*  values for which @p __binary_pred returns true.
*  unique() is stable, so the relative order of elements that are
*  not removed is unchanged.
*  Elements between the end of the resulting sequence and @p __last
*  are still present, but their value is unspecified.
*/
template<typename _ForwardIterator, typename _BinaryPredicate>
_ForwardIterator
unique(_ForwardIterator __first, _ForwardIterator __last,
_BinaryPredicate __binary_pred)
{
// concept requirements
__glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
_ForwardIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
typename iterator_traits<_ForwardIterator>::value_type,
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

// Skip the beginning, if already unique.
__first = _GLIBCXX_STD_A::adjacent_find(__first, __last, __binary_pred);
if (__first == __last)
return __last;

// Do the real copy work.
_ForwardIterator __dest = __first;
++__first;
while (++__first != __last)
if (!bool(__binary_pred(*__dest, *__first)))
*++__dest = _GLIBCXX_MOVE(*__first);
return ++__dest;
}

/**
*  This is an uglified unique_copy(_InputIterator, _InputIterator,
*                                  _OutputIterator)
*  overloaded for forward iterators and output iterator as result.
*/
template<typename _ForwardIterator, typename _OutputIterator>
_OutputIterator
__unique_copy(_ForwardIterator __first, _ForwardIterator __last,
_OutputIterator __result,
forward_iterator_tag, output_iterator_tag)
{
// concept requirements -- taken care of in dispatching function
_ForwardIterator __next = __first;
*__result = *__first;
while (++__next != __last)
if (!(*__first == *__next))
{
__first = __next;
*++__result = *__first;
}
return ++__result;
}

/**
*  This is an uglified unique_copy(_InputIterator, _InputIterator,
*                                  _OutputIterator)
*  overloaded for input iterators and output iterator as result.
*/
template<typename _InputIterator, typename _OutputIterator>
_OutputIterator
__unique_copy(_InputIterator __first, _InputIterator __last,
_OutputIterator __result,
input_iterator_tag, output_iterator_tag)
{
// concept requirements -- taken care of in dispatching function
typename iterator_traits<_InputIterator>::value_type __value = *__first;
*__result = __value;
while (++__first != __last)
if (!(__value == *__first))
{
__value = *__first;
*++__result = __value;
}
return ++__result;
}

/**
*  This is an uglified unique_copy(_InputIterator, _InputIterator,
*                                  _OutputIterator)
*  overloaded for input iterators and forward iterator as result.
*/
template<typename _InputIterator, typename _ForwardIterator>
_ForwardIterator
__unique_copy(_InputIterator __first, _InputIterator __last,
_ForwardIterator __result,
input_iterator_tag, forward_iterator_tag)
{
// concept requirements -- taken care of in dispatching function
*__result = *__first;
while (++__first != __last)
if (!(*__result == *__first))
*++__result = *__first;
return ++__result;
}

/**
*  This is an uglified
*  unique_copy(_InputIterator, _InputIterator, _OutputIterator,
*              _BinaryPredicate)
*  overloaded for forward iterators and output iterator as result.
*/
template<typename _ForwardIterator, typename _OutputIterator,
typename _BinaryPredicate>
_OutputIterator
__unique_copy(_ForwardIterator __first, _ForwardIterator __last,
_OutputIterator __result, _BinaryPredicate __binary_pred,
forward_iterator_tag, output_iterator_tag)
{
// concept requirements -- iterators already checked
__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
typename iterator_traits<_ForwardIterator>::value_type,
typename iterator_traits<_ForwardIterator>::value_type>)

_ForwardIterator __next = __first;
*__result = *__first;
while (++__next != __last)
if (!bool(__binary_pred(*__first, *__next)))
{
__first = __next;
*++__result = *__first;
}
return ++__result;
}

/**
*  This is an uglified
*  unique_copy(_InputIterator, _InputIterator, _OutputIterator,
*              _BinaryPredicate)
*  overloaded for input iterators and output iterator as result.
*/
template<typename _InputIterator, typename _OutputIterator,
typename _BinaryPredicate>
_OutputIterator
__unique_copy(_InputIterator __first, _InputIterator __last,
_OutputIterator __result, _BinaryPredicate __binary_pred,
input_iterator_tag, output_iterator_tag)
{
// concept requirements -- iterators already checked
__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
typename iterator_traits<_InputIterator>::value_type,
typename iterator_traits<_InputIterator>::value_type>)

typename iterator_traits<_InputIterator>::value_type __value = *__first;
*__result = __value;
while (++__first != __last)
if (!bool(__binary_pred(__value, *__first)))
{
__value = *__first;
*++__result = __value;
}
return ++__result;
}

/**
*  This is an uglified
*  unique_copy(_InputIterator, _InputIterator, _OutputIterator,
*              _BinaryPredicate)
*  overloaded for input iterators and forward iterator as result.
*/
template<typename _InputIterator, typename _ForwardIterator,
typename _BinaryPredicate>
_ForwardIterator
__unique_copy(_InputIterator __first, _InputIterator __last,
_ForwardIterator __result, _BinaryPredicate __binary_pred,
input_iterator_tag, forward_iterator_tag)
{
// concept requirements -- iterators already checked
__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
typename iterator_traits<_ForwardIterator>::value_type,
typename iterator_traits<_InputIterator>::value_type>)

*__result = *__first;
while (++__first != __last)
if (!bool(__binary_pred(*__result, *__first)))
*++__result = *__first;
return ++__result;
}

/**
*  This is an uglified reverse(_BidirectionalIterator,
*                              _BidirectionalIterator)
*  overloaded for bidirectional iterators.
*/
template<typename _BidirectionalIterator>
void
__reverse(_BidirectionalIterator __first, _BidirectionalIterator __last,
bidirectional_iterator_tag)
{
while (true)
if (__first == __last || __first == --__last)
return;
else
{
std::iter_swap(__first, __last);
++__first;
}
}

/**
*  This is an uglified reverse(_BidirectionalIterator,
*                              _BidirectionalIterator)
*  overloaded for random access iterators.
*/
template<typename _RandomAccessIterator>
void
__reverse(_RandomAccessIterator __first, _RandomAccessIterator __last,
random_access_iterator_tag)
{
if (__first == __last)
return;
--__last;
while (__first < __last)
{
std::iter_swap(__first, __last);
++__first;
--__last;
}
}

/**
*  @brief Reverse a sequence.
*  @ingroup mutating_algorithms
*  @param  __first  A bidirectional iterator.
*  @param  __last   A bidirectional iterator.
*  @return   reverse() returns no value.
*
*  Reverses the order of the elements in the range @p [__first,__last),
*  so that the first element becomes the last etc.
*  For every @c i such that @p 0<=i<=(__last-__first)/2), @p reverse()
*  swaps @p *(__first+i) and @p *(__last-(i+1))
*/
template<typename _BidirectionalIterator>
inline void
reverse(_BidirectionalIterator __first, _BidirectionalIterator __last)
{
// concept requirements
__glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<
_BidirectionalIterator>)
__glibcxx_requires_valid_range(__first, __last);
std::__reverse(__first, __last, std::__iterator_category(__first));
}

/**
*  @brief Copy a sequence, reversing its elements.
*  @ingroup mutating_algorithms
*  @param  __first   A bidirectional iterator.
*  @param  __last    A bidirectional iterator.
*  @param  __result  An output iterator.
*  @return  An iterator designating the end of the resulting sequence.
*
*  Copies the elements in the range @p [__first,__last) to the
*  range @p [__result,__result+(__last-__first)) such that the
*  order of the elements is reversed.  For every @c i such that @p
*  0<=i<=(__last-__first), @p reverse_copy() performs the
*  assignment @p *(__result+(__last-__first)-i) = *(__first+i).
*  The ranges @p [__first,__last) and @p
*  [__result,__result+(__last-__first)) must not overlap.
*/
template<typename _BidirectionalIterator, typename _OutputIterator>
_OutputIterator
reverse_copy(_BidirectionalIterator __first, _BidirectionalIterator __last,
_OutputIterator __result)
{
// concept requirements
__glibcxx_function_requires(_BidirectionalIteratorConcept<
_BidirectionalIterator>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
typename iterator_traits<_BidirectionalIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

while (__first != __last)
{
--__last;
*__result = *__last;
++__result;
}
return __result;
}

/**
*  This is a helper function for the rotate algorithm specialized on RAIs.
*  It returns the greatest common divisor of two integer values.
*/
template<typename _EuclideanRingElement>
_EuclideanRingElement
__gcd(_EuclideanRingElement __m, _EuclideanRingElement __n)
{
while (__n != 0)
{
_EuclideanRingElement __t = __m % __n;
__m = __n;
__n = __t;
}
return __m;
}

/// This is a helper function for the rotate algorithm.
template<typename _ForwardIterator>
void
__rotate(_ForwardIterator __first,
_ForwardIterator __middle,
_ForwardIterator __last,
forward_iterator_tag)
{
if (__first == __middle || __last  == __middle)
return;

_ForwardIterator __first2 = __middle;
do
{
std::iter_swap(__first, __first2);
++__first;
++__first2;
if (__first == __middle)
__middle = __first2;
}
while (__first2 != __last);

__first2 = __middle;

while (__first2 != __last)
{
std::iter_swap(__first, __first2);
++__first;
++__first2;
if (__first == __middle)
__middle = __first2;
else if (__first2 == __last)
__first2 = __middle;
}
}

/// This is a helper function for the rotate algorithm.
template<typename _BidirectionalIterator>
void
__rotate(_BidirectionalIterator __first,
_BidirectionalIterator __middle,
_BidirectionalIterator __last,
bidirectional_iterator_tag)
{
// concept requirements
__glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<
_BidirectionalIterator>)

if (__first == __middle || __last  == __middle)
return;

std::__reverse(__first,  __middle, bidirectional_iterator_tag());
std::__reverse(__middle, __last,   bidirectional_iterator_tag());

while (__first != __middle && __middle != __last)
{
std::iter_swap(__first, --__last);
++__first;
}

if (__first == __middle)
std::__reverse(__middle, __last,   bidirectional_iterator_tag());
else
std::__reverse(__first,  __middle, bidirectional_iterator_tag());
}

/// This is a helper function for the rotate algorithm.
template<typename _RandomAccessIterator>
void
__rotate(_RandomAccessIterator __first,
_RandomAccessIterator __middle,
_RandomAccessIterator __last,
random_access_iterator_tag)
{
// concept requirements
__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
_RandomAccessIterator>)

if (__first == __middle || __last  == __middle)
return;

typedef typename iterator_traits<_RandomAccessIterator>::difference_type
_Distance;
typedef typename iterator_traits<_RandomAccessIterator>::value_type
_ValueType;

_Distance __n = __last   - __first;
_Distance __k = __middle - __first;

if (__k == __n - __k)
{
std::swap_ranges(__first, __middle, __middle);
return;
}

_RandomAccessIterator __p = __first;

for (;;)
{
if (__k < __n - __k)
{
if (__is_pod(_ValueType) && __k == 1)
{
_ValueType __t = _GLIBCXX_MOVE(*__p);
_GLIBCXX_MOVE3(__p + 1, __p + __n, __p);
*(__p + __n - 1) = _GLIBCXX_MOVE(__t);
return;
}
_RandomAccessIterator __q = __p + __k;
for (_Distance __i = 0; __i < __n - __k; ++ __i)
{
std::iter_swap(__p, __q);
++__p;
++__q;
}
__n %= __k;
if (__n == 0)
return;
std::swap(__n, __k);
__k = __n - __k;
}
else
{
__k = __n - __k;
if (__is_pod(_ValueType) && __k == 1)
{
_ValueType __t = _GLIBCXX_MOVE(*(__p + __n - 1));
_GLIBCXX_MOVE_BACKWARD3(__p, __p + __n - 1, __p + __n);
*__p = _GLIBCXX_MOVE(__t);
return;
}
_RandomAccessIterator __q = __p + __n;
__p = __q - __k;
for (_Distance __i = 0; __i < __n - __k; ++ __i)
{
--__p;
--__q;
std::iter_swap(__p, __q);
}
__n %= __k;
if (__n == 0)
return;
std::swap(__n, __k);
}
}
}

/**
*  @brief Rotate the elements of a sequence.
*  @ingroup mutating_algorithms
*  @param  __first   A forward iterator.
*  @param  __middle  A forward iterator.
*  @param  __last    A forward iterator.
*  @return  Nothing.
*
*  Rotates the elements of the range @p [__first,__last) by
*  @p (__middle - __first) positions so that the element at @p __middle
*  is moved to @p __first, the element at @p __middle+1 is moved to
*  @p __first+1 and so on for each element in the range
*  @p [__first,__last).
*
*  This effectively swaps the ranges @p [__first,__middle) and
*  @p [__middle,__last).
*
*  Performs
*   @p *(__first+(n+(__last-__middle))%(__last-__first))=*(__first+n)
*  for each @p n in the range @p [0,__last-__first).
*/
template<typename _ForwardIterator>
inline void
rotate(_ForwardIterator __first, _ForwardIterator __middle,
_ForwardIterator __last)
{
// concept requirements
__glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
_ForwardIterator>)
__glibcxx_requires_valid_range(__first, __middle);
__glibcxx_requires_valid_range(__middle, __last);

typedef typename iterator_traits<_ForwardIterator>::iterator_category
_IterType;
std::__rotate(__first, __middle, __last, _IterType());
}

/**
*  @brief Copy a sequence, rotating its elements.
*  @ingroup mutating_algorithms
*  @param  __first   A forward iterator.
*  @param  __middle  A forward iterator.
*  @param  __last    A forward iterator.
*  @param  __result  An output iterator.
*  @return   An iterator designating the end of the resulting sequence.
*
*  Copies the elements of the range @p [__first,__last) to the
*  range beginning at @result, rotating the copied elements by
*  @p (__middle-__first) positions so that the element at @p __middle
*  is moved to @p __result, the element at @p __middle+1 is moved
*  to @p __result+1 and so on for each element in the range @p
*  [__first,__last).
*
*  Performs
*  @p *(__result+(n+(__last-__middle))%(__last-__first))=*(__first+n)
*  for each @p n in the range @p [0,__last-__first).
*/
template<typename _ForwardIterator, typename _OutputIterator>
_OutputIterator
rotate_copy(_ForwardIterator __first, _ForwardIterator __middle,
_ForwardIterator __last, _OutputIterator __result)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __middle);
__glibcxx_requires_valid_range(__middle, __last);

return std::copy(__first, __middle,
std::copy(__middle, __last, __result));
}

/// This is a helper function...
template<typename _ForwardIterator, typename _Predicate>
_ForwardIterator
__partition(_ForwardIterator __first, _ForwardIterator __last,
_Predicate __pred, forward_iterator_tag)
{
if (__first == __last)
return __first;

while (__pred(*__first))
if (++__first == __last)
return __first;

_ForwardIterator __next = __first;

while (++__next != __last)
if (__pred(*__next))
{
std::iter_swap(__first, __next);
++__first;
}

return __first;
}

/// This is a helper function...
template<typename _BidirectionalIterator, typename _Predicate>
_BidirectionalIterator
__partition(_BidirectionalIterator __first, _BidirectionalIterator __last,
_Predicate __pred, bidirectional_iterator_tag)
{
while (true)
{
while (true)
if (__first == __last)
return __first;
else if (__pred(*__first))
++__first;
else
break;
--__last;
while (true)
if (__first == __last)
return __first;
else if (!bool(__pred(*__last)))
--__last;
else
break;
std::iter_swap(__first, __last);
++__first;
}
}

// partition

/// This is a helper function...
/// Requires __len != 0 and !__pred(*__first),
/// same as __stable_partition_adaptive.
template<typename _ForwardIterator, typename _Predicate, typename _Distance>
_ForwardIterator
__inplace_stable_partition(_ForwardIterator __first,
_Predicate __pred, _Distance __len)
{
if (__len == 1)
return __first;
_ForwardIterator __middle = __first;
std::advance(__middle, __len / 2);
_ForwardIterator __left_split =
std::__inplace_stable_partition(__first, __pred, __len / 2);
// Advance past true-predicate values to satisfy this
// function's preconditions.
_Distance __right_len = __len - __len / 2;
_ForwardIterator __right_split =
std::__find_if_not_n(__middle, __right_len, __pred);
if (__right_len)
__right_split = std::__inplace_stable_partition(__middle,
__pred,
__right_len);
std::rotate(__left_split, __middle, __right_split);
std::advance(__left_split, std::distance(__middle, __right_split));
return __left_split;
}

/// This is a helper function...
/// Requires __first != __last and !__pred(*__first)
/// and __len == distance(__first, __last).
///
/// !__pred(*__first) allows us to guarantee that we don't
/// move-assign an element onto itself.
template<typename _ForwardIterator, typename _Pointer, typename _Predicate,
typename _Distance>
_ForwardIterator
__stable_partition_adaptive(_ForwardIterator __first,
_ForwardIterator __last,
_Predicate __pred, _Distance __len,
_Pointer __buffer,
_Distance __buffer_size)
{
if (__len <= __buffer_size)
{
_ForwardIterator __result1 = __first;
_Pointer __result2 = __buffer;
// The precondition guarantees that !__pred(*__first), so
// move that element to the buffer before starting the loop.
// This ensures that we only call __pred once per element.
*__result2 = _GLIBCXX_MOVE(*__first);
++__result2;
++__first;
for (; __first != __last; ++__first)
if (__pred(*__first))
{
*__result1 = _GLIBCXX_MOVE(*__first);
++__result1;
}
else
{
*__result2 = _GLIBCXX_MOVE(*__first);
++__result2;
}
_GLIBCXX_MOVE3(__buffer, __result2, __result1);
return __result1;
}
else
{
_ForwardIterator __middle = __first;
std::advance(__middle, __len / 2);
_ForwardIterator __left_split =
std::__stable_partition_adaptive(__first, __middle, __pred,
__len / 2, __buffer,
__buffer_size);
// Advance past true-predicate values to satisfy this
// function's preconditions.
_Distance __right_len = __len - __len / 2;
_ForwardIterator __right_split =
std::__find_if_not_n(__middle, __right_len, __pred);
if (__right_len)
__right_split =
std::__stable_partition_adaptive(__right_split, __last, __pred,
__right_len,
__buffer, __buffer_size);
std::rotate(__left_split, __middle, __right_split);
std::advance(__left_split, std::distance(__middle, __right_split));
return __left_split;
}
}

/**
*  @brief Move elements for which a predicate is true to the beginning
*         of a sequence, preserving relative ordering.
*  @ingroup mutating_algorithms
*  @param  __first   A forward iterator.
*  @param  __last    A forward iterator.
*  @param  __pred    A predicate functor.
*  @return  An iterator @p middle such that @p __pred(i) is true for each
*  iterator @p i in the range @p [first,middle) and false for each @p i
*  in the range @p [middle,last).
*
*  Performs the same function as @p partition() with the additional
*  guarantee that the relative ordering of elements in each group is
*  preserved, so any two elements @p x and @p y in the range
*  @p [__first,__last) such that @p __pred(x)==__pred(y) will have the same
*  relative ordering after calling @p stable_partition().
*/
template<typename _ForwardIterator, typename _Predicate>
_ForwardIterator
stable_partition(_ForwardIterator __first, _ForwardIterator __last,
_Predicate __pred)
{
// concept requirements
__glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
_ForwardIterator>)
__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

__first = std::__find_if_not(__first, __last, __pred);

if (__first == __last)
return __first;
else
{
typedef typename iterator_traits<_ForwardIterator>::value_type
_ValueType;
typedef typename iterator_traits<_ForwardIterator>::difference_type
_DistanceType;

_Temporary_buffer<_ForwardIterator, _ValueType> __buf(__first,
__last);
if (__buf.size() > 0)
return
std::__stable_partition_adaptive(__first, __last, __pred,
_DistanceType(__buf.requested_size()),
__buf.begin(),
_DistanceType(__buf.size()));
else
return
std::__inplace_stable_partition(__first, __pred,
_DistanceType(__buf.requested_size()));
}
}

/// This is a helper function for the sort routines.
template<typename _RandomAccessIterator>
void
__heap_select(_RandomAccessIterator __first,
_RandomAccessIterator __middle,
_RandomAccessIterator __last)
{
std::make_heap(__first, __middle);
for (_RandomAccessIterator __i = __middle; __i < __last; ++__i)
if (*__i < *__first)
std::__pop_heap(__first, __middle, __i);
}

/// This is a helper function for the sort routines.
template<typename _RandomAccessIterator, typename _Compare>
void
__heap_select(_RandomAccessIterator __first,
_RandomAccessIterator __middle,
_RandomAccessIterator __last, _Compare __comp)
{
std::make_heap(__first, __middle, __comp);
for (_RandomAccessIterator __i = __middle; __i < __last; ++__i)
if (__comp(*__i, *__first))
std::__pop_heap(__first, __middle, __i, __comp);
}

// partial_sort

/**
*  @brief Copy the smallest elements of a sequence.
*  @ingroup sorting_algorithms
*  @param  __first   An iterator.
*  @param  __last    Another iterator.
*  @param  __result_first   A random-access iterator.
*  @param  __result_last    Another random-access iterator.
*  @return   An iterator indicating the end of the resulting sequence.
*
*  Copies and sorts the smallest N values from the range @p [__first,__last)
*  to the range beginning at @p __result_first, where the number of
*  elements to be copied, @p N, is the smaller of @p (__last-__first) and
*  @p (__result_last-__result_first).
*  After the sort if @e i and @e j are iterators in the range
*  @p [__result_first,__result_first+N) such that i precedes j then
*  *j<*i is false.
*  The value returned is @p __result_first+N.
*/
template<typename _InputIterator, typename _RandomAccessIterator>
_RandomAccessIterator
partial_sort_copy(_InputIterator __first, _InputIterator __last,
_RandomAccessIterator __result_first,
_RandomAccessIterator __result_last)
{
typedef typename iterator_traits<_InputIterator>::value_type
_InputValueType;
typedef typename iterator_traits<_RandomAccessIterator>::value_type
_OutputValueType;
typedef typename iterator_traits<_RandomAccessIterator>::difference_type
_DistanceType;

// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_ConvertibleConcept<_InputValueType,
_OutputValueType>)
__glibcxx_function_requires(_LessThanOpConcept<_InputValueType,
_OutputValueType>)
__glibcxx_function_requires(_LessThanComparableConcept<_OutputValueType>)
__glibcxx_requires_valid_range(__first, __last);
__glibcxx_requires_valid_range(__result_first, __result_last);

if (__result_first == __result_last)
return __result_last;
_RandomAccessIterator __result_real_last = __result_first;
while(__first != __last && __result_real_last != __result_last)
{
*__result_real_last = *__first;
++__result_real_last;
++__first;
}
std::make_heap(__result_first, __result_real_last);
while (__first != __last)
{
if (*__first < *__result_first)
std::__adjust_heap(__result_first, _DistanceType(0),
_DistanceType(__result_real_last
- __result_first),
_InputValueType(*__first));
++__first;
}
std::sort_heap(__result_first, __result_real_last);
return __result_real_last;
}

/**
*  @brief Copy the smallest elements of a sequence using a predicate for
*         comparison.
*  @ingroup sorting_algorithms
*  @param  __first   An input iterator.
*  @param  __last    Another input iterator.
*  @param  __result_first   A random-access iterator.
*  @param  __result_last    Another random-access iterator.
*  @param  __comp    A comparison functor.
*  @return   An iterator indicating the end of the resulting sequence.
*
*  Copies and sorts the smallest N values from the range @p [__first,__last)
*  to the range beginning at @p result_first, where the number of
*  elements to be copied, @p N, is the smaller of @p (__last-__first) and
*  @p (__result_last-__result_first).
*  After the sort if @e i and @e j are iterators in the range
*  @p [__result_first,__result_first+N) such that i precedes j then
*  @p __comp(*j,*i) is false.
*  The value returned is @p __result_first+N.
*/
template<typename _InputIterator, typename _RandomAccessIterator, typename _Compare>
_RandomAccessIterator
partial_sort_copy(_InputIterator __first, _InputIterator __last,
_RandomAccessIterator __result_first,
_RandomAccessIterator __result_last,
_Compare __comp)
{
typedef typename iterator_traits<_InputIterator>::value_type
_InputValueType;
typedef typename iterator_traits<_RandomAccessIterator>::value_type
_OutputValueType;
typedef typename iterator_traits<_RandomAccessIterator>::difference_type
_DistanceType;

// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
_RandomAccessIterator>)
__glibcxx_function_requires(_ConvertibleConcept<_InputValueType,
_OutputValueType>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_InputValueType, _OutputValueType>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_OutputValueType, _OutputValueType>)
__glibcxx_requires_valid_range(__first, __last);
__glibcxx_requires_valid_range(__result_first, __result_last);

if (__result_first == __result_last)
return __result_last;
_RandomAccessIterator __result_real_last = __result_first;
while(__first != __last && __result_real_last != __result_last)
{
*__result_real_last = *__first;
++__result_real_last;
++__first;
}
std::make_heap(__result_first, __result_real_last, __comp);
while (__first != __last)
{
if (__comp(*__first, *__result_first))
std::__adjust_heap(__result_first, _DistanceType(0),
_DistanceType(__result_real_last
- __result_first),
_InputValueType(*__first),
__comp);
++__first;
}
std::sort_heap(__result_first, __result_real_last, __comp);
return __result_real_last;
}

/// This is a helper function for the sort routine.
template<typename _RandomAccessIterator>
void
__unguarded_linear_insert(_RandomAccessIterator __last)
{
typename iterator_traits<_RandomAccessIterator>::value_type
__val = _GLIBCXX_MOVE(*__last);
_RandomAccessIterator __next = __last;
--__next;
while (__val < *__next)
{
*__last = _GLIBCXX_MOVE(*__next);
__last = __next;
--__next;
}
*__last = _GLIBCXX_MOVE(__val);
}

/// This is a helper function for the sort routine.
template<typename _RandomAccessIterator, typename _Compare>
void
__unguarded_linear_insert(_RandomAccessIterator __last,
_Compare __comp)
{
typename iterator_traits<_RandomAccessIterator>::value_type
__val = _GLIBCXX_MOVE(*__last);
_RandomAccessIterator __next = __last;
--__next;
while (__comp(__val, *__next))
{
*__last = _GLIBCXX_MOVE(*__next);
__last = __next;
--__next;
}
*__last = _GLIBCXX_MOVE(__val);
}

/// This is a helper function for the sort routine.
template<typename _RandomAccessIterator>
void
__insertion_sort(_RandomAccessIterator __first,
_RandomAccessIterator __last)
{
if (__first == __last)
return;

for (_RandomAccessIterator __i = __first + 1; __i != __last; ++__i)
{
if (*__i < *__first)
{
typename iterator_traits<_RandomAccessIterator>::value_type
__val = _GLIBCXX_MOVE(*__i);
_GLIBCXX_MOVE_BACKWARD3(__first, __i, __i + 1);
*__first = _GLIBCXX_MOVE(__val);
}
else
std::__unguarded_linear_insert(__i);
}
}

/// This is a helper function for the sort routine.
template<typename _RandomAccessIterator, typename _Compare>
void
__insertion_sort(_RandomAccessIterator __first,
_RandomAccessIterator __last, _Compare __comp)
{
if (__first == __last) return;

for (_RandomAccessIterator __i = __first + 1; __i != __last; ++__i)
{
if (__comp(*__i, *__first))
{
typename iterator_traits<_RandomAccessIterator>::value_type
__val = _GLIBCXX_MOVE(*__i);
_GLIBCXX_MOVE_BACKWARD3(__first, __i, __i + 1);
*__first = _GLIBCXX_MOVE(__val);
}
else
std::__unguarded_linear_insert(__i, __comp);
}
}

/// This is a helper function for the sort routine.
template<typename _RandomAccessIterator>
inline void
__unguarded_insertion_sort(_RandomAccessIterator __first,
_RandomAccessIterator __last)
{
typedef typename iterator_traits<_RandomAccessIterator>::value_type
_ValueType;

for (_RandomAccessIterator __i = __first; __i != __last; ++__i)
std::__unguarded_linear_insert(__i);
}

/// This is a helper function for the sort routine.
template<typename _RandomAccessIterator, typename _Compare>
inline void
__unguarded_insertion_sort(_RandomAccessIterator __first,
_RandomAccessIterator __last, _Compare __comp)
{
typedef typename iterator_traits<_RandomAccessIterator>::value_type
_ValueType;

for (_RandomAccessIterator __i = __first; __i != __last; ++__i)
std::__unguarded_linear_insert(__i, __comp);
}

/**
*  @doctodo
*  This controls some aspect of the sort routines.
*/
enum { _S_threshold = 16 };

/// This is a helper function for the sort routine.
template<typename _RandomAccessIterator>
void
__final_insertion_sort(_RandomAccessIterator __first,
_RandomAccessIterator __last)
{
if (__last - __first > int(_S_threshold))
{
std::__insertion_sort(__first, __first + int(_S_threshold));
std::__unguarded_insertion_sort(__first + int(_S_threshold), __last);
}
else
std::__insertion_sort(__first, __last);
}

/// This is a helper function for the sort routine.
template<typename _RandomAccessIterator, typename _Compare>
void
__final_insertion_sort(_RandomAccessIterator __first,
_RandomAccessIterator __last, _Compare __comp)
{
if (__last - __first > int(_S_threshold))
{
std::__insertion_sort(__first, __first + int(_S_threshold), __comp);
std::__unguarded_insertion_sort(__first + int(_S_threshold), __last,
__comp);
}
else
std::__insertion_sort(__first, __last, __comp);
}

/// This is a helper function...
template<typename _RandomAccessIterator, typename _Tp>
_RandomAccessIterator
__unguarded_partition(_RandomAccessIterator __first,
_RandomAccessIterator __last, const _Tp& __pivot)
{
while (true)
{
while (*__first < __pivot)
++__first;
--__last;
while (__pivot < *__last)
--__last;
if (!(__first < __last))
return __first;
std::iter_swap(__first, __last);
++__first;
}
}

/// This is a helper function...
template<typename _RandomAccessIterator, typename _Tp, typename _Compare>
_RandomAccessIterator
__unguarded_partition(_RandomAccessIterator __first,
_RandomAccessIterator __last,
const _Tp& __pivot, _Compare __comp)
{
while (true)
{
while (__comp(*__first, __pivot))
++__first;
--__last;
while (__comp(__pivot, *__last))
--__last;
if (!(__first < __last))
return __first;
std::iter_swap(__first, __last);
++__first;
}
}

/// This is a helper function...
template<typename _RandomAccessIterator>
inline _RandomAccessIterator
__unguarded_partition_pivot(_RandomAccessIterator __first,
_RandomAccessIterator __last)
{
_RandomAccessIterator __mid = __first + (__last - __first) / 2;
std::__move_median_first(__first, __mid, (__last - 1));
return std::__unguarded_partition(__first + 1, __last, *__first);
}

/// This is a helper function...
template<typename _RandomAccessIterator, typename _Compare>
inline _RandomAccessIterator
__unguarded_partition_pivot(_RandomAccessIterator __first,
_RandomAccessIterator __last, _Compare __comp)
{
_RandomAccessIterator __mid = __first + (__last - __first) / 2;
std::__move_median_first(__first, __mid, (__last - 1), __comp);
return std::__unguarded_partition(__first + 1, __last, *__first, __comp);
}

/// This is a helper function for the sort routine.
template<typename _RandomAccessIterator, typename _Size>
void
__introsort_loop(_RandomAccessIterator __first,
_RandomAccessIterator __last,
_Size __depth_limit)
{
while (__last - __first > int(_S_threshold))
{
if (__depth_limit == 0)
{
_GLIBCXX_STD_A::partial_sort(__first, __last, __last);
return;
}
--__depth_limit;
_RandomAccessIterator __cut =
std::__unguarded_partition_pivot(__first, __last);
std::__introsort_loop(__cut, __last, __depth_limit);
__last = __cut;
}
}

/// This is a helper function for the sort routine.
template<typename _RandomAccessIterator, typename _Size, typename _Compare>
void
__introsort_loop(_RandomAccessIterator __first,
_RandomAccessIterator __last,
_Size __depth_limit, _Compare __comp)
{
while (__last - __first > int(_S_threshold))
{
if (__depth_limit == 0)
{
_GLIBCXX_STD_A::partial_sort(__first, __last, __last, __comp);
return;
}
--__depth_limit;
_RandomAccessIterator __cut =
std::__unguarded_partition_pivot(__first, __last, __comp);
std::__introsort_loop(__cut, __last, __depth_limit, __comp);
__last = __cut;
}
}

// sort

template<typename _RandomAccessIterator, typename _Size>
void
__introselect(_RandomAccessIterator __first, _RandomAccessIterator __nth,
_RandomAccessIterator __last, _Size __depth_limit)
{
typedef typename iterator_traits<_RandomAccessIterator>::value_type
_ValueType;

while (__last - __first > 3)
{
if (__depth_limit == 0)
{
std::__heap_select(__first, __nth + 1, __last);

// Place the nth largest element in its final position.
std::iter_swap(__first, __nth);
return;
}
--__depth_limit;
_RandomAccessIterator __cut =
std::__unguarded_partition_pivot(__first, __last);
if (__cut <= __nth)
__first = __cut;
else
__last = __cut;
}
std::__insertion_sort(__first, __last);
}

template<typename _RandomAccessIterator, typename _Size, typename _Compare>
void
__introselect(_RandomAccessIterator __first, _RandomAccessIterator __nth,
_RandomAccessIterator __last, _Size __depth_limit,
_Compare __comp)
{
typedef typename iterator_traits<_RandomAccessIterator>::value_type
_ValueType;

while (__last - __first > 3)
{
if (__depth_limit == 0)
{
std::__heap_select(__first, __nth + 1, __last, __comp);
// Place the nth largest element in its final position.
std::iter_swap(__first, __nth);
return;
}
--__depth_limit;
_RandomAccessIterator __cut =
std::__unguarded_partition_pivot(__first, __last, __comp);
if (__cut <= __nth)
__first = __cut;
else
__last = __cut;
}
std::__insertion_sort(__first, __last, __comp);
}

// nth_element

// lower_bound moved to stl_algobase.h

/**
*  @brief Finds the first position in which @p __val could be inserted
*         without changing the ordering.
*  @ingroup binary_search_algorithms
*  @param  __first   An iterator.
*  @param  __last    Another iterator.
*  @param  __val     The search term.
*  @param  __comp    A functor to use for comparisons.
*  @return An iterator pointing to the first element <em>not less
*           than</em> @p __val, or end() if every element is less
*           than @p __val.
*  @ingroup binary_search_algorithms
*
*  The comparison function should have the same effects on ordering as
*  the function used for the initial sort.
*/
template<typename _ForwardIterator, typename _Tp, typename _Compare>
_ForwardIterator
lower_bound(_ForwardIterator __first, _ForwardIterator __last,
const _Tp& __val, _Compare __comp)
{
typedef typename iterator_traits<_ForwardIterator>::value_type
_ValueType;
typedef typename iterator_traits<_ForwardIterator>::difference_type
_DistanceType;

// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_ValueType, _Tp>)
__glibcxx_requires_partitioned_lower_pred(__first, __last,
__val, __comp);

_DistanceType __len = std::distance(__first, __last);

while (__len > 0)
{
_DistanceType __half = __len >> 1;
_ForwardIterator __middle = __first;
std::advance(__middle, __half);
if (__comp(*__middle, __val))
{
__first = __middle;
++__first;
__len = __len - __half - 1;
}
else
__len = __half;
}
return __first;
}

/**
*  @brief Finds the last position in which @p __val could be inserted
*         without changing the ordering.
*  @ingroup binary_search_algorithms
*  @param  __first   An iterator.
*  @param  __last    Another iterator.
*  @param  __val     The search term.
*  @return  An iterator pointing to the first element greater than @p __val,
*           or end() if no elements are greater than @p __val.
*  @ingroup binary_search_algorithms
*/
template<typename _ForwardIterator, typename _Tp>
_ForwardIterator
upper_bound(_ForwardIterator __first, _ForwardIterator __last,
const _Tp& __val)
{
typedef typename iterator_traits<_ForwardIterator>::value_type
_ValueType;
typedef typename iterator_traits<_ForwardIterator>::difference_type
_DistanceType;

// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_LessThanOpConcept<_Tp, _ValueType>)
__glibcxx_requires_partitioned_upper(__first, __last, __val);

_DistanceType __len = std::distance(__first, __last);

while (__len > 0)
{
_DistanceType __half = __len >> 1;
_ForwardIterator __middle = __first;
std::advance(__middle, __half);
if (__val < *__middle)
__len = __half;
else
{
__first = __middle;
++__first;
__len = __len - __half - 1;
}
}
return __first;
}

/**
*  @brief Finds the last position in which @p __val could be inserted
*         without changing the ordering.
*  @ingroup binary_search_algorithms
*  @param  __first   An iterator.
*  @param  __last    Another iterator.
*  @param  __val     The search term.
*  @param  __comp    A functor to use for comparisons.
*  @return  An iterator pointing to the first element greater than @p __val,
*           or end() if no elements are greater than @p __val.
*  @ingroup binary_search_algorithms
*
*  The comparison function should have the same effects on ordering as
*  the function used for the initial sort.
*/
template<typename _ForwardIterator, typename _Tp, typename _Compare>
_ForwardIterator
upper_bound(_ForwardIterator __first, _ForwardIterator __last,
const _Tp& __val, _Compare __comp)
{
typedef typename iterator_traits<_ForwardIterator>::value_type
_ValueType;
typedef typename iterator_traits<_ForwardIterator>::difference_type
_DistanceType;

// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_Tp, _ValueType>)
__glibcxx_requires_partitioned_upper_pred(__first, __last,
__val, __comp);

_DistanceType __len = std::distance(__first, __last);

while (__len > 0)
{
_DistanceType __half = __len >> 1;
_ForwardIterator __middle = __first;
std::advance(__middle, __half);
if (__comp(__val, *__middle))
__len = __half;
else
{
__first = __middle;
++__first;
__len = __len - __half - 1;
}
}
return __first;
}

/**
*  @brief Finds the largest subrange in which @p __val could be inserted
*         at any place in it without changing the ordering.
*  @ingroup binary_search_algorithms
*  @param  __first   An iterator.
*  @param  __last    Another iterator.
*  @param  __val     The search term.
*  @return  An pair of iterators defining the subrange.
*  @ingroup binary_search_algorithms
*
*  This is equivalent to
*  @code
*    std::make_pair(lower_bound(__first, __last, __val),
*                   upper_bound(__first, __last, __val))
*  @endcode
*  but does not actually call those functions.
*/
template<typename _ForwardIterator, typename _Tp>
pair<_ForwardIterator, _ForwardIterator>
equal_range(_ForwardIterator __first, _ForwardIterator __last,
const _Tp& __val)
{
typedef typename iterator_traits<_ForwardIterator>::value_type
_ValueType;
typedef typename iterator_traits<_ForwardIterator>::difference_type
_DistanceType;

// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_LessThanOpConcept<_ValueType, _Tp>)
__glibcxx_function_requires(_LessThanOpConcept<_Tp, _ValueType>)
__glibcxx_requires_partitioned_lower(__first, __last, __val);
__glibcxx_requires_partitioned_upper(__first, __last, __val);

_DistanceType __len = std::distance(__first, __last);

while (__len > 0)
{
_DistanceType __half = __len >> 1;
_ForwardIterator __middle = __first;
std::advance(__middle, __half);
if (*__middle < __val)
{
__first = __middle;
++__first;
__len = __len - __half - 1;
}
else if (__val < *__middle)
__len = __half;
else
{
_ForwardIterator __left = std::lower_bound(__first, __middle,
__val);
std::advance(__first, __len);
_ForwardIterator __right = std::upper_bound(++__middle, __first,
__val);
return pair<_ForwardIterator, _ForwardIterator>(__left, __right);
}
}
return pair<_ForwardIterator, _ForwardIterator>(__first, __first);
}

/**
*  @brief Finds the largest subrange in which @p __val could be inserted
*         at any place in it without changing the ordering.
*  @param  __first   An iterator.
*  @param  __last    Another iterator.
*  @param  __val     The search term.
*  @param  __comp    A functor to use for comparisons.
*  @return  An pair of iterators defining the subrange.
*  @ingroup binary_search_algorithms
*
*  This is equivalent to
*  @code
*    std::make_pair(lower_bound(__first, __last, __val, __comp),
*                   upper_bound(__first, __last, __val, __comp))
*  @endcode
*  but does not actually call those functions.
*/
template<typename _ForwardIterator, typename _Tp, typename _Compare>
pair<_ForwardIterator, _ForwardIterator>
equal_range(_ForwardIterator __first, _ForwardIterator __last,
const _Tp& __val, _Compare __comp)
{
typedef typename iterator_traits<_ForwardIterator>::value_type
_ValueType;
typedef typename iterator_traits<_ForwardIterator>::difference_type
_DistanceType;

// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_ValueType, _Tp>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_Tp, _ValueType>)
__glibcxx_requires_partitioned_lower_pred(__first, __last,
__val, __comp);
__glibcxx_requires_partitioned_upper_pred(__first, __last,
__val, __comp);

_DistanceType __len = std::distance(__first, __last);

while (__len > 0)
{
_DistanceType __half = __len >> 1;
_ForwardIterator __middle = __first;
std::advance(__middle, __half);
if (__comp(*__middle, __val))
{
__first = __middle;
++__first;
__len = __len - __half - 1;
}
else if (__comp(__val, *__middle))
__len = __half;
else
{
_ForwardIterator __left = std::lower_bound(__first, __middle,
__val, __comp);
std::advance(__first, __len);
_ForwardIterator __right = std::upper_bound(++__middle, __first,
__val, __comp);
return pair<_ForwardIterator, _ForwardIterator>(__left, __right);
}
}
return pair<_ForwardIterator, _ForwardIterator>(__first, __first);
}

/**
*  @brief Determines whether an element exists in a range.
*  @ingroup binary_search_algorithms
*  @param  __first   An iterator.
*  @param  __last    Another iterator.
*  @param  __val     The search term.
*  @return True if @p __val (or its equivalent) is in [@p
*  __first,@p __last ].
*
*  Note that this does not actually return an iterator to @p __val.  For
*  that, use std::find or a container's specialized find member functions.
*/
template<typename _ForwardIterator, typename _Tp>
bool
binary_search(_ForwardIterator __first, _ForwardIterator __last,
const _Tp& __val)
{
typedef typename iterator_traits<_ForwardIterator>::value_type
_ValueType;

// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_LessThanOpConcept<_Tp, _ValueType>)
__glibcxx_requires_partitioned_lower(__first, __last, __val);
__glibcxx_requires_partitioned_upper(__first, __last, __val);

_ForwardIterator __i = std::lower_bound(__first, __last, __val);
return __i != __last && !(__val < *__i);
}

/**
*  @brief Determines whether an element exists in a range.
*  @ingroup binary_search_algorithms
*  @param  __first   An iterator.
*  @param  __last    Another iterator.
*  @param  __val     The search term.
*  @param  __comp    A functor to use for comparisons.
*  @return  True if @p __val (or its equivalent) is in @p [__first,__last].
*
*  Note that this does not actually return an iterator to @p __val.  For
*  that, use std::find or a container's specialized find member functions.
*
*  The comparison function should have the same effects on ordering as
*  the function used for the initial sort.
*/
template<typename _ForwardIterator, typename _Tp, typename _Compare>
bool
binary_search(_ForwardIterator __first, _ForwardIterator __last,
const _Tp& __val, _Compare __comp)
{
typedef typename iterator_traits<_ForwardIterator>::value_type
_ValueType;

// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_Tp, _ValueType>)
__glibcxx_requires_partitioned_lower_pred(__first, __last,
__val, __comp);
__glibcxx_requires_partitioned_upper_pred(__first, __last,
__val, __comp);

_ForwardIterator __i = std::lower_bound(__first, __last, __val, __comp);
return __i != __last && !bool(__comp(__val, *__i));
}

// merge

/// This is a helper function for the __merge_adaptive routines.
template<typename _InputIterator1, typename _InputIterator2,
typename _OutputIterator>
void
__move_merge_adaptive(_InputIterator1 __first1, _InputIterator1 __last1,
_InputIterator2 __first2, _InputIterator2 __last2,
_OutputIterator __result)
{
while (__first1 != __last1 && __first2 != __last2)
{
if (*__first2 < *__first1)
{
*__result = _GLIBCXX_MOVE(*__first2);
++__first2;
}
else
{
*__result = _GLIBCXX_MOVE(*__first1);
++__first1;
}
++__result;
}
if (__first1 != __last1)
_GLIBCXX_MOVE3(__first1, __last1, __result);
}

/// This is a helper function for the __merge_adaptive routines.
template<typename _InputIterator1, typename _InputIterator2,
typename _OutputIterator, typename _Compare>
void
__move_merge_adaptive(_InputIterator1 __first1, _InputIterator1 __last1,
_InputIterator2 __first2, _InputIterator2 __last2,
_OutputIterator __result, _Compare __comp)
{
while (__first1 != __last1 && __first2 != __last2)
{
if (__comp(*__first2, *__first1))
{
*__result = _GLIBCXX_MOVE(*__first2);
++__first2;
}
else
{
*__result = _GLIBCXX_MOVE(*__first1);
++__first1;
}
++__result;
}
if (__first1 != __last1)
_GLIBCXX_MOVE3(__first1, __last1, __result);
}

/// This is a helper function for the __merge_adaptive routines.
template<typename _BidirectionalIterator1, typename _BidirectionalIterator2,
typename _BidirectionalIterator3>
void
__move_merge_adaptive_backward(_BidirectionalIterator1 __first1,
_BidirectionalIterator1 __last1,
_BidirectionalIterator2 __first2,
_BidirectionalIterator2 __last2,
_BidirectionalIterator3 __result)
{
if (__first1 == __last1)
{
_GLIBCXX_MOVE_BACKWARD3(__first2, __last2, __result);
return;
}
else if (__first2 == __last2)
return;

--__last1;
--__last2;
while (true)
{
if (*__last2 < *__last1)
{
*--__result = _GLIBCXX_MOVE(*__last1);
if (__first1 == __last1)
{
_GLIBCXX_MOVE_BACKWARD3(__first2, ++__last2, __result);
return;
}
--__last1;
}
else
{
*--__result = _GLIBCXX_MOVE(*__last2);
if (__first2 == __last2)
return;
--__last2;
}
}
}

/// This is a helper function for the __merge_adaptive routines.
template<typename _BidirectionalIterator1, typename _BidirectionalIterator2,
typename _BidirectionalIterator3, typename _Compare>
void
__move_merge_adaptive_backward(_BidirectionalIterator1 __first1,
_BidirectionalIterator1 __last1,
_BidirectionalIterator2 __first2,
_BidirectionalIterator2 __last2,
_BidirectionalIterator3 __result,
_Compare __comp)
{
if (__first1 == __last1)
{
_GLIBCXX_MOVE_BACKWARD3(__first2, __last2, __result);
return;
}
else if (__first2 == __last2)
return;

--__last1;
--__last2;
while (true)
{
if (__comp(*__last2, *__last1))
{
*--__result = _GLIBCXX_MOVE(*__last1);
if (__first1 == __last1)
{
_GLIBCXX_MOVE_BACKWARD3(__first2, ++__last2, __result);
return;
}
--__last1;
}
else
{
*--__result = _GLIBCXX_MOVE(*__last2);
if (__first2 == __last2)
return;
--__last2;
}
}
}

/// This is a helper function for the merge routines.
template<typename _BidirectionalIterator1, typename _BidirectionalIterator2,
typename _Distance>
_BidirectionalIterator1
__rotate_adaptive(_BidirectionalIterator1 __first,
_BidirectionalIterator1 __middle,
_BidirectionalIterator1 __last,
_Distance __len1, _Distance __len2,
_BidirectionalIterator2 __buffer,
_Distance __buffer_size)
{
_BidirectionalIterator2 __buffer_end;
if (__len1 > __len2 && __len2 <= __buffer_size)
{
if (__len2)
{
__buffer_end = _GLIBCXX_MOVE3(__middle, __last, __buffer);
_GLIBCXX_MOVE_BACKWARD3(__first, __middle, __last);
return _GLIBCXX_MOVE3(__buffer, __buffer_end, __first);
}
else
return __first;
}
else if (__len1 <= __buffer_size)
{
if (__len1)
{
__buffer_end = _GLIBCXX_MOVE3(__first, __middle, __buffer);
_GLIBCXX_MOVE3(__middle, __last, __first);
return _GLIBCXX_MOVE_BACKWARD3(__buffer, __buffer_end, __last);
}
else
return __last;
}
else
{
std::rotate(__first, __middle, __last);
std::advance(__first, std::distance(__middle, __last));
return __first;
}
}

/// This is a helper function for the merge routines.
template<typename _BidirectionalIterator, typename _Distance,
typename _Pointer>
void
__merge_adaptive(_BidirectionalIterator __first,
_BidirectionalIterator __middle,
_BidirectionalIterator __last,
_Distance __len1, _Distance __len2,
_Pointer __buffer, _Distance __buffer_size)
{
if (__len1 <= __len2 && __len1 <= __buffer_size)
{
_Pointer __buffer_end = _GLIBCXX_MOVE3(__first, __middle, __buffer);
std::__move_merge_adaptive(__buffer, __buffer_end, __middle, __last,
__first);
}
else if (__len2 <= __buffer_size)
{
_Pointer __buffer_end = _GLIBCXX_MOVE3(__middle, __last, __buffer);
std::__move_merge_adaptive_backward(__first, __middle, __buffer,
__buffer_end, __last);
}
else
{
_BidirectionalIterator __first_cut = __first;
_BidirectionalIterator __second_cut = __middle;
_Distance __len11 = 0;
_Distance __len22 = 0;
if (__len1 > __len2)
{
__len11 = __len1 / 2;
std::advance(__first_cut, __len11);
__second_cut = std::lower_bound(__middle, __last,
*__first_cut);
__len22 = std::distance(__middle, __second_cut);
}
else
{
__len22 = __len2 / 2;
std::advance(__second_cut, __len22);
__first_cut = std::upper_bound(__first, __middle,
*__second_cut);
__len11 = std::distance(__first, __first_cut);
}
_BidirectionalIterator __new_middle =
std::__rotate_adaptive(__first_cut, __middle, __second_cut,
__len1 - __len11, __len22, __buffer,
__buffer_size);
std::__merge_adaptive(__first, __first_cut, __new_middle, __len11,
__len22, __buffer, __buffer_size);
std::__merge_adaptive(__new_middle, __second_cut, __last,
__len1 - __len11,
__len2 - __len22, __buffer, __buffer_size);
}
}

/// This is a helper function for the merge routines.
template<typename _BidirectionalIterator, typename _Distance,
typename _Pointer, typename _Compare>
void
__merge_adaptive(_BidirectionalIterator __first,
_BidirectionalIterator __middle,
_BidirectionalIterator __last,
_Distance __len1, _Distance __len2,
_Pointer __buffer, _Distance __buffer_size,
_Compare __comp)
{
if (__len1 <= __len2 && __len1 <= __buffer_size)
{
_Pointer __buffer_end = _GLIBCXX_MOVE3(__first, __middle, __buffer);
std::__move_merge_adaptive(__buffer, __buffer_end, __middle, __last,
__first, __comp);
}
else if (__len2 <= __buffer_size)
{
_Pointer __buffer_end = _GLIBCXX_MOVE3(__middle, __last, __buffer);
std::__move_merge_adaptive_backward(__first, __middle, __buffer,
__buffer_end, __last, __comp);
}
else
{
_BidirectionalIterator __first_cut = __first;
_BidirectionalIterator __second_cut = __middle;
_Distance __len11 = 0;
_Distance __len22 = 0;
if (__len1 > __len2)
{
__len11 = __len1 / 2;
std::advance(__first_cut, __len11);
__second_cut = std::lower_bound(__middle, __last, *__first_cut,
__comp);
__len22 = std::distance(__middle, __second_cut);
}
else
{
__len22 = __len2 / 2;
std::advance(__second_cut, __len22);
__first_cut = std::upper_bound(__first, __middle, *__second_cut,
__comp);
__len11 = std::distance(__first, __first_cut);
}
_BidirectionalIterator __new_middle =
std::__rotate_adaptive(__first_cut, __middle, __second_cut,
__len1 - __len11, __len22, __buffer,
__buffer_size);
std::__merge_adaptive(__first, __first_cut, __new_middle, __len11,
__len22, __buffer, __buffer_size, __comp);
std::__merge_adaptive(__new_middle, __second_cut, __last,
__len1 - __len11,
__len2 - __len22, __buffer,
__buffer_size, __comp);
}
}

/// This is a helper function for the merge routines.
template<typename _BidirectionalIterator, typename _Distance>
void
__merge_without_buffer(_BidirectionalIterator __first,
_BidirectionalIterator __middle,
_BidirectionalIterator __last,
_Distance __len1, _Distance __len2)
{
if (__len1 == 0 || __len2 == 0)
return;
if (__len1 + __len2 == 2)
{
if (*__middle < *__first)
std::iter_swap(__first, __middle);
return;
}
_BidirectionalIterator __first_cut = __first;
_BidirectionalIterator __second_cut = __middle;
_Distance __len11 = 0;
_Distance __len22 = 0;
if (__len1 > __len2)
{
__len11 = __len1 / 2;
std::advance(__first_cut, __len11);
__second_cut = std::lower_bound(__middle, __last, *__first_cut);
__len22 = std::distance(__middle, __second_cut);
}
else
{
__len22 = __len2 / 2;
std::advance(__second_cut, __len22);
__first_cut = std::upper_bound(__first, __middle, *__second_cut);
__len11 = std::distance(__first, __first_cut);
}
std::rotate(__first_cut, __middle, __second_cut);
_BidirectionalIterator __new_middle = __first_cut;
std::advance(__new_middle, std::distance(__middle, __second_cut));
std::__merge_without_buffer(__first, __first_cut, __new_middle,
__len11, __len22);
std::__merge_without_buffer(__new_middle, __second_cut, __last,
__len1 - __len11, __len2 - __len22);
}

/// This is a helper function for the merge routines.
template<typename _BidirectionalIterator, typename _Distance,
typename _Compare>
void
__merge_without_buffer(_BidirectionalIterator __first,
_BidirectionalIterator __middle,
_BidirectionalIterator __last,
_Distance __len1, _Distance __len2,
_Compare __comp)
{
if (__len1 == 0 || __len2 == 0)
return;
if (__len1 + __len2 == 2)
{
if (__comp(*__middle, *__first))
std::iter_swap(__first, __middle);
return;
}
_BidirectionalIterator __first_cut = __first;
_BidirectionalIterator __second_cut = __middle;
_Distance __len11 = 0;
_Distance __len22 = 0;
if (__len1 > __len2)
{
__len11 = __len1 / 2;
std::advance(__first_cut, __len11);
__second_cut = std::lower_bound(__middle, __last, *__first_cut,
__comp);
__len22 = std::distance(__middle, __second_cut);
}
else
{
__len22 = __len2 / 2;
std::advance(__second_cut, __len22);
__first_cut = std::upper_bound(__first, __middle, *__second_cut,
__comp);
__len11 = std::distance(__first, __first_cut);
}
std::rotate(__first_cut, __middle, __second_cut);
_BidirectionalIterator __new_middle = __first_cut;
std::advance(__new_middle, std::distance(__middle, __second_cut));
std::__merge_without_buffer(__first, __first_cut, __new_middle,
__len11, __len22, __comp);
std::__merge_without_buffer(__new_middle, __second_cut, __last,
__len1 - __len11, __len2 - __len22, __comp);
}

/**
*  @brief Merges two sorted ranges in place.
*  @ingroup sorting_algorithms
*  @param  __first   An iterator.
*  @param  __middle  Another iterator.
*  @param  __last    Another iterator.
*  @return  Nothing.
*
*  Merges two sorted and consecutive ranges, [__first,__middle) and
*  [__middle,__last), and puts the result in [__first,__last).  The
*  output will be sorted.  The sort is @e stable, that is, for
*  equivalent elements in the two ranges, elements from the first
*  range will always come before elements from the second.
*
*  If enough additional memory is available, this takes (__last-__first)-1
*  comparisons.  Otherwise an NlogN algorithm is used, where N is
*  distance(__first,__last).
*/
template<typename _BidirectionalIterator>
void
inplace_merge(_BidirectionalIterator __first,
_BidirectionalIterator __middle,
_BidirectionalIterator __last)
{
typedef typename iterator_traits<_BidirectionalIterator>::value_type
_ValueType;
typedef typename iterator_traits<_BidirectionalIterator>::difference_type
_DistanceType;

// concept requirements
__glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<
_BidirectionalIterator>)
__glibcxx_function_requires(_LessThanComparableConcept<_ValueType>)
__glibcxx_requires_sorted(__first, __middle);
__glibcxx_requires_sorted(__middle, __last);

if (__first == __middle || __middle == __last)
return;

_DistanceType __len1 = std::distance(__first, __middle);
_DistanceType __len2 = std::distance(__middle, __last);

_Temporary_buffer<_BidirectionalIterator, _ValueType> __buf(__first,
__last);
if (__buf.begin() == 0)
std::__merge_without_buffer(__first, __middle, __last, __len1, __len2);
else
std::__merge_adaptive(__first, __middle, __last, __len1, __len2,
__buf.begin(), _DistanceType(__buf.size()));
}

/**
*  @brief Merges two sorted ranges in place.
*  @ingroup sorting_algorithms
*  @param  __first   An iterator.
*  @param  __middle  Another iterator.
*  @param  __last    Another iterator.
*  @param  __comp    A functor to use for comparisons.
*  @return  Nothing.
*
*  Merges two sorted and consecutive ranges, [__first,__middle) and
*  [middle,last), and puts the result in [__first,__last).  The output will
*  be sorted.  The sort is @e stable, that is, for equivalent
*  elements in the two ranges, elements from the first range will always
*  come before elements from the second.
*
*  If enough additional memory is available, this takes (__last-__first)-1
*  comparisons.  Otherwise an NlogN algorithm is used, where N is
*  distance(__first,__last).
*
*  The comparison function should have the same effects on ordering as
*  the function used for the initial sort.
*/
template<typename _BidirectionalIterator, typename _Compare>
void
inplace_merge(_BidirectionalIterator __first,
_BidirectionalIterator __middle,
_BidirectionalIterator __last,
_Compare __comp)
{
typedef typename iterator_traits<_BidirectionalIterator>::value_type
_ValueType;
typedef typename iterator_traits<_BidirectionalIterator>::difference_type
_DistanceType;

// concept requirements
__glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<
_BidirectionalIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_ValueType, _ValueType>)
__glibcxx_requires_sorted_pred(__first, __middle, __comp);
__glibcxx_requires_sorted_pred(__middle, __last, __comp);

if (__first == __middle || __middle == __last)
return;

const _DistanceType __len1 = std::distance(__first, __middle);
const _DistanceType __len2 = std::distance(__middle, __last);

_Temporary_buffer<_BidirectionalIterator, _ValueType> __buf(__first,
__last);
if (__buf.begin() == 0)
std::__merge_without_buffer(__first, __middle, __last, __len1,
__len2, __comp);
else
std::__merge_adaptive(__first, __middle, __last, __len1, __len2,
__buf.begin(), _DistanceType(__buf.size()),
__comp);
}

/// This is a helper function for the __merge_sort_loop routines.
template<typename _InputIterator1, typename _InputIterator2,
typename _OutputIterator>
_OutputIterator
__move_merge(_InputIterator1 __first1, _InputIterator1 __last1,
_InputIterator2 __first2, _InputIterator2 __last2,
_OutputIterator __result)
{
while (__first1 != __last1 && __first2 != __last2)
{
if (*__first2 < *__first1)
{
*__result = _GLIBCXX_MOVE(*__first2);
++__first2;
}
else
{
*__result = _GLIBCXX_MOVE(*__first1);
++__first1;
}
++__result;
}
return _GLIBCXX_MOVE3(__first2, __last2,
_GLIBCXX_MOVE3(__first1, __last1,
__result));
}

/// This is a helper function for the __merge_sort_loop routines.
template<typename _InputIterator1, typename _InputIterator2,
typename _OutputIterator, typename _Compare>
_OutputIterator
__move_merge(_InputIterator1 __first1, _InputIterator1 __last1,
_InputIterator2 __first2, _InputIterator2 __last2,
_OutputIterator __result, _Compare __comp)
{
while (__first1 != __last1 && __first2 != __last2)
{
if (__comp(*__first2, *__first1))
{
*__result = _GLIBCXX_MOVE(*__first2);
++__first2;
}
else
{
*__result = _GLIBCXX_MOVE(*__first1);
++__first1;
}
++__result;
}
return _GLIBCXX_MOVE3(__first2, __last2,
_GLIBCXX_MOVE3(__first1, __last1,
__result));
}

template<typename _RandomAccessIterator1, typename _RandomAccessIterator2,
typename _Distance>
void
__merge_sort_loop(_RandomAccessIterator1 __first,
_RandomAccessIterator1 __last,
_RandomAccessIterator2 __result,
_Distance __step_size)
{
const _Distance __two_step = 2 * __step_size;

while (__last - __first >= __two_step)
{
__result = std::__move_merge(__first, __first + __step_size,
__first + __step_size,
__first + __two_step, __result);
__first += __two_step;
}

__step_size = std::min(_Distance(__last - __first), __step_size);
std::__move_merge(__first, __first + __step_size,
__first + __step_size, __last, __result);
}

template<typename _RandomAccessIterator1, typename _RandomAccessIterator2,
typename _Distance, typename _Compare>
void
__merge_sort_loop(_RandomAccessIterator1 __first,
_RandomAccessIterator1 __last,
_RandomAccessIterator2 __result, _Distance __step_size,
_Compare __comp)
{
const _Distance __two_step = 2 * __step_size;

while (__last - __first >= __two_step)
{
__result = std::__move_merge(__first, __first + __step_size,
__first + __step_size,
__first + __two_step,
__result, __comp);
__first += __two_step;
}
__step_size = std::min(_Distance(__last - __first), __step_size);

std::__move_merge(__first,__first + __step_size,
__first + __step_size, __last, __result, __comp);
}

template<typename _RandomAccessIterator, typename _Distance>
void
__chunk_insertion_sort(_RandomAccessIterator __first,
_RandomAccessIterator __last,
_Distance __chunk_size)
{
while (__last - __first >= __chunk_size)
{
std::__insertion_sort(__first, __first + __chunk_size);
__first += __chunk_size;
}
std::__insertion_sort(__first, __last);
}

template<typename _RandomAccessIterator, typename _Distance,
typename _Compare>
void
__chunk_insertion_sort(_RandomAccessIterator __first,
_RandomAccessIterator __last,
_Distance __chunk_size, _Compare __comp)
{
while (__last - __first >= __chunk_size)
{
std::__insertion_sort(__first, __first + __chunk_size, __comp);
__first += __chunk_size;
}
std::__insertion_sort(__first, __last, __comp);
}

enum { _S_chunk_size = 7 };

template<typename _RandomAccessIterator, typename _Pointer>
void
__merge_sort_with_buffer(_RandomAccessIterator __first,
_RandomAccessIterator __last,
_Pointer __buffer)
{
typedef typename iterator_traits<_RandomAccessIterator>::difference_type
_Distance;

const _Distance __len = __last - __first;
const _Pointer __buffer_last = __buffer + __len;

_Distance __step_size = _S_chunk_size;
std::__chunk_insertion_sort(__first, __last, __step_size);

while (__step_size < __len)
{
std::__merge_sort_loop(__first, __last, __buffer, __step_size);
__step_size *= 2;
std::__merge_sort_loop(__buffer, __buffer_last, __first, __step_size);
__step_size *= 2;
}
}

template<typename _RandomAccessIterator, typename _Pointer, typename _Compare>
void
__merge_sort_with_buffer(_RandomAccessIterator __first,
_RandomAccessIterator __last,
_Pointer __buffer, _Compare __comp)
{
typedef typename iterator_traits<_RandomAccessIterator>::difference_type
_Distance;

const _Distance __len = __last - __first;
const _Pointer __buffer_last = __buffer + __len;

_Distance __step_size = _S_chunk_size;
std::__chunk_insertion_sort(__first, __last, __step_size, __comp);

while (__step_size < __len)
{
std::__merge_sort_loop(__first, __last, __buffer,
__step_size, __comp);
__step_size *= 2;
std::__merge_sort_loop(__buffer, __buffer_last, __first,
__step_size, __comp);
__step_size *= 2;
}
}

template<typename _RandomAccessIterator, typename _Pointer,
typename _Distance>
void
__stable_sort_adaptive(_RandomAccessIterator __first,
_RandomAccessIterator __last,
_Pointer __buffer, _Distance __buffer_size)
{
const _Distance __len = (__last - __first + 1) / 2;
const _RandomAccessIterator __middle = __first + __len;
if (__len > __buffer_size)
{
std::__stable_sort_adaptive(__first, __middle,
__buffer, __buffer_size);
std::__stable_sort_adaptive(__middle, __last,
__buffer, __buffer_size);
}
else
{
std::__merge_sort_with_buffer(__first, __middle, __buffer);
std::__merge_sort_with_buffer(__middle, __last, __buffer);
}
std::__merge_adaptive(__first, __middle, __last,
_Distance(__middle - __first),
_Distance(__last - __middle),
__buffer, __buffer_size);
}

template<typename _RandomAccessIterator, typename _Pointer,
typename _Distance, typename _Compare>
void
__stable_sort_adaptive(_RandomAccessIterator __first,
_RandomAccessIterator __last,
_Pointer __buffer, _Distance __buffer_size,
_Compare __comp)
{
const _Distance __len = (__last - __first + 1) / 2;
const _RandomAccessIterator __middle = __first + __len;
if (__len > __buffer_size)
{
std::__stable_sort_adaptive(__first, __middle, __buffer,
__buffer_size, __comp);
std::__stable_sort_adaptive(__middle, __last, __buffer,
__buffer_size, __comp);
}
else
{
std::__merge_sort_with_buffer(__first, __middle, __buffer, __comp);
std::__merge_sort_with_buffer(__middle, __last, __buffer, __comp);
}
std::__merge_adaptive(__first, __middle, __last,
_Distance(__middle - __first),
_Distance(__last - __middle),
__buffer, __buffer_size,
__comp);
}

/// This is a helper function for the stable sorting routines.
template<typename _RandomAccessIterator>
void
__inplace_stable_sort(_RandomAccessIterator __first,
_RandomAccessIterator __last)
{
if (__last - __first < 15)
{
std::__insertion_sort(__first, __last);
return;
}
_RandomAccessIterator __middle = __first + (__last - __first) / 2;
std::__inplace_stable_sort(__first, __middle);
std::__inplace_stable_sort(__middle, __last);
std::__merge_without_buffer(__first, __middle, __last,
__middle - __first,
__last - __middle);
}

/// This is a helper function for the stable sorting routines.
template<typename _RandomAccessIterator, typename _Compare>
void
__inplace_stable_sort(_RandomAccessIterator __first,
_RandomAccessIterator __last, _Compare __comp)
{
if (__last - __first < 15)
{
std::__insertion_sort(__first, __last, __comp);
return;
}
_RandomAccessIterator __middle = __first + (__last - __first) / 2;
std::__inplace_stable_sort(__first, __middle, __comp);
std::__inplace_stable_sort(__middle, __last, __comp);
std::__merge_without_buffer(__first, __middle, __last,
__middle - __first,
__last - __middle,
__comp);
}

// stable_sort

// Set algorithms: includes, set_union, set_intersection, set_difference,
// set_symmetric_difference.  All of these algorithms have the precondition
// that their input ranges are sorted and the postcondition that their output
// ranges are sorted.

/**
*  @brief Determines whether all elements of a sequence exists in a range.
*  @param  __first1  Start of search range.
*  @param  __last1   End of search range.
*  @param  __first2  Start of sequence
*  @param  __last2   End of sequence.
*  @return  True if each element in [__first2,__last2) is contained in order
*  within [__first1,__last1).  False otherwise.
*  @ingroup set_algorithms
*
*  This operation expects both [__first1,__last1) and
*  [__first2,__last2) to be sorted.  Searches for the presence of
*  each element in [__first2,__last2) within [__first1,__last1).
*  The iterators over each range only move forward, so this is a
*  linear algorithm.  If an element in [__first2,__last2) is not
*  found before the search iterator reaches @p __last2, false is
*  returned.
*/
template<typename _InputIterator1, typename _InputIterator2>
bool
includes(_InputIterator1 __first1, _InputIterator1 __last1,
_InputIterator2 __first2, _InputIterator2 __last2)
{
typedef typename iterator_traits<_InputIterator1>::value_type
_ValueType1;
typedef typename iterator_traits<_InputIterator2>::value_type
_ValueType2;

// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
__glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
__glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
__glibcxx_requires_sorted_set(__first1, __last1, __first2);
__glibcxx_requires_sorted_set(__first2, __last2, __first1);

while (__first1 != __last1 && __first2 != __last2)
if (*__first2 < *__first1)
return false;
else if(*__first1 < *__first2)
++__first1;
else
++__first1, ++__first2;

return __first2 == __last2;
}

/**
*  @brief Determines whether all elements of a sequence exists in a range
*  using comparison.
*  @ingroup set_algorithms
*  @param  __first1  Start of search range.
*  @param  __last1   End of search range.
*  @param  __first2  Start of sequence
*  @param  __last2   End of sequence.
*  @param  __comp    Comparison function to use.
*  @return True if each element in [__first2,__last2) is contained
*  in order within [__first1,__last1) according to comp.  False
*  otherwise.  @ingroup set_algorithms
*
*  This operation expects both [__first1,__last1) and
*  [__first2,__last2) to be sorted.  Searches for the presence of
*  each element in [__first2,__last2) within [__first1,__last1),
*  using comp to decide.  The iterators over each range only move
*  forward, so this is a linear algorithm.  If an element in
*  [__first2,__last2) is not found before the search iterator
*  reaches @p __last2, false is returned.
*/
template<typename _InputIterator1, typename _InputIterator2,
typename _Compare>
bool
includes(_InputIterator1 __first1, _InputIterator1 __last1,
_InputIterator2 __first2, _InputIterator2 __last2,
_Compare __comp)
{
typedef typename iterator_traits<_InputIterator1>::value_type
_ValueType1;
typedef typename iterator_traits<_InputIterator2>::value_type
_ValueType2;

// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_ValueType1, _ValueType2>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_ValueType2, _ValueType1>)
__glibcxx_requires_sorted_set_pred(__first1, __last1, __first2, __comp);
__glibcxx_requires_sorted_set_pred(__first2, __last2, __first1, __comp);

while (__first1 != __last1 && __first2 != __last2)
if (__comp(*__first2, *__first1))
return false;
else if(__comp(*__first1, *__first2))
++__first1;
else
++__first1, ++__first2;

return __first2 == __last2;
}

// nth_element
// merge
// set_difference
// set_intersection
// set_union
// stable_sort
// set_symmetric_difference
// min_element
// max_element

/**
*  @brief  Permute range into the next @e dictionary ordering.
*  @ingroup sorting_algorithms
*  @param  __first  Start of range.
*  @param  __last   End of range.
*  @return  False if wrapped to first permutation, true otherwise.
*
*  Treats all permutations of the range as a set of @e dictionary sorted
*  sequences.  Permutes the current sequence into the next one of this set.
*  Returns true if there are more sequences to generate.  If the sequence
*  is the largest of the set, the smallest is generated and false returned.
*/
template<typename _BidirectionalIterator>
bool
next_permutation(_BidirectionalIterator __first,
_BidirectionalIterator __last)
{
// concept requirements
__glibcxx_function_requires(_BidirectionalIteratorConcept<
_BidirectionalIterator>)
__glibcxx_function_requires(_LessThanComparableConcept<
typename iterator_traits<_BidirectionalIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

if (__first == __last)
return false;
_BidirectionalIterator __i = __first;
++__i;
if (__i == __last)
return false;
__i = __last;
--__i;

for(;;)
{
_BidirectionalIterator __ii = __i;
--__i;
if (*__i < *__ii)
{
_BidirectionalIterator __j = __last;
while (!(*__i < *--__j))
{}
std::iter_swap(__i, __j);
std::reverse(__ii, __last);
return true;
}
if (__i == __first)
{
std::reverse(__first, __last);
return false;
}
}
}

/**
*  @brief  Permute range into the next @e dictionary ordering using
*          comparison functor.
*  @ingroup sorting_algorithms
*  @param  __first  Start of range.
*  @param  __last   End of range.
*  @param  __comp   A comparison functor.
*  @return  False if wrapped to first permutation, true otherwise.
*
*  Treats all permutations of the range [__first,__last) as a set of
*  @e dictionary sorted sequences ordered by @p __comp.  Permutes the current
*  sequence into the next one of this set.  Returns true if there are more
*  sequences to generate.  If the sequence is the largest of the set, the
*  smallest is generated and false returned.
*/
template<typename _BidirectionalIterator, typename _Compare>
bool
next_permutation(_BidirectionalIterator __first,
_BidirectionalIterator __last, _Compare __comp)
{
// concept requirements
__glibcxx_function_requires(_BidirectionalIteratorConcept<
_BidirectionalIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
typename iterator_traits<_BidirectionalIterator>::value_type,
typename iterator_traits<_BidirectionalIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

if (__first == __last)
return false;
_BidirectionalIterator __i = __first;
++__i;
if (__i == __last)
return false;
__i = __last;
--__i;

for(;;)
{
_BidirectionalIterator __ii = __i;
--__i;
if (__comp(*__i, *__ii))
{
_BidirectionalIterator __j = __last;
while (!bool(__comp(*__i, *--__j)))
{}
std::iter_swap(__i, __j);
std::reverse(__ii, __last);
return true;
}
if (__i == __first)
{
std::reverse(__first, __last);
return false;
}
}
}

/**
*  @brief  Permute range into the previous @e dictionary ordering.
*  @ingroup sorting_algorithms
*  @param  __first  Start of range.
*  @param  __last   End of range.
*  @return  False if wrapped to last permutation, true otherwise.
*
*  Treats all permutations of the range as a set of @e dictionary sorted
*  sequences.  Permutes the current sequence into the previous one of this
*  set.  Returns true if there are more sequences to generate.  If the
*  sequence is the smallest of the set, the largest is generated and false
*  returned.
*/
template<typename _BidirectionalIterator>
bool
prev_permutation(_BidirectionalIterator __first,
_BidirectionalIterator __last)
{
// concept requirements
__glibcxx_function_requires(_BidirectionalIteratorConcept<
_BidirectionalIterator>)
__glibcxx_function_requires(_LessThanComparableConcept<
typename iterator_traits<_BidirectionalIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

if (__first == __last)
return false;
_BidirectionalIterator __i = __first;
++__i;
if (__i == __last)
return false;
__i = __last;
--__i;

for(;;)
{
_BidirectionalIterator __ii = __i;
--__i;
if (*__ii < *__i)
{
_BidirectionalIterator __j = __last;
while (!(*--__j < *__i))
{}
std::iter_swap(__i, __j);
std::reverse(__ii, __last);
return true;
}
if (__i == __first)
{
std::reverse(__first, __last);
return false;
}
}
}

/**
*  @brief  Permute range into the previous @e dictionary ordering using
*          comparison functor.
*  @ingroup sorting_algorithms
*  @param  __first  Start of range.
*  @param  __last   End of range.
*  @param  __comp   A comparison functor.
*  @return  False if wrapped to last permutation, true otherwise.
*
*  Treats all permutations of the range [__first,__last) as a set of
*  @e dictionary sorted sequences ordered by @p __comp.  Permutes the current
*  sequence into the previous one of this set.  Returns true if there are
*  more sequences to generate.  If the sequence is the smallest of the set,
*  the largest is generated and false returned.
*/
template<typename _BidirectionalIterator, typename _Compare>
bool
prev_permutation(_BidirectionalIterator __first,
_BidirectionalIterator __last, _Compare __comp)
{
// concept requirements
__glibcxx_function_requires(_BidirectionalIteratorConcept<
_BidirectionalIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
typename iterator_traits<_BidirectionalIterator>::value_type,
typename iterator_traits<_BidirectionalIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

if (__first == __last)
return false;
_BidirectionalIterator __i = __first;
++__i;
if (__i == __last)
return false;
__i = __last;
--__i;

for(;;)
{
_BidirectionalIterator __ii = __i;
--__i;
if (__comp(*__ii, *__i))
{
_BidirectionalIterator __j = __last;
while (!bool(__comp(*--__j, *__i)))
{}
std::iter_swap(__i, __j);
std::reverse(__ii, __last);
return true;
}
if (__i == __first)
{
std::reverse(__first, __last);
return false;
}
}
}

// replace
// replace_if

/**
*  @brief Copy a sequence, replacing each element of one value with another
*         value.
*  @param  __first      An input iterator.
*  @param  __last       An input iterator.
*  @param  __result     An output iterator.
*  @param  __old_value  The value to be replaced.
*  @param  __new_value  The replacement value.
*  @return   The end of the output sequence, @p result+(last-first).
*
*  Copies each element in the input range @p [__first,__last) to the
*  output range @p [__result,__result+(__last-__first)) replacing elements
*  equal to @p __old_value with @p __new_value.
*/
template<typename _InputIterator, typename _OutputIterator, typename _Tp>
_OutputIterator
replace_copy(_InputIterator __first, _InputIterator __last,
_OutputIterator __result,
const _Tp& __old_value, const _Tp& __new_value)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
typename iterator_traits<_InputIterator>::value_type>)
__glibcxx_function_requires(_EqualOpConcept<
typename iterator_traits<_InputIterator>::value_type, _Tp>)
__glibcxx_requires_valid_range(__first, __last);

for (; __first != __last; ++__first, ++__result)
if (*__first == __old_value)
*__result = __new_value;
else
*__result = *__first;
return __result;
}

/**
*  @brief Copy a sequence, replacing each value for which a predicate
*         returns true with another value.
*  @ingroup mutating_algorithms
*  @param  __first      An input iterator.
*  @param  __last       An input iterator.
*  @param  __result     An output iterator.
*  @param  __pred       A predicate.
*  @param  __new_value  The replacement value.
*  @return   The end of the output sequence, @p __result+(__last-__first).
*
*  Copies each element in the range @p [__first,__last) to the range
*  @p [__result,__result+(__last-__first)) replacing elements for which
*  @p __pred returns true with @p __new_value.
*/
template<typename _InputIterator, typename _OutputIterator,
typename _Predicate, typename _Tp>
_OutputIterator
replace_copy_if(_InputIterator __first, _InputIterator __last,
_OutputIterator __result,
_Predicate __pred, const _Tp& __new_value)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
typename iterator_traits<_InputIterator>::value_type>)
__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
typename iterator_traits<_InputIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

for (; __first != __last; ++__first, ++__result)
if (__pred(*__first))
*__result = __new_value;
else
*__result = *__first;
return __result;
}

#ifdef __GXX_EXPERIMENTAL_CXX0X__
/**
*  @brief  Determines whether the elements of a sequence are sorted.
*  @ingroup sorting_algorithms
*  @param  __first   An iterator.
*  @param  __last    Another iterator.
*  @return  True if the elements are sorted, false otherwise.
*/
template<typename _ForwardIterator>
inline bool
is_sorted(_ForwardIterator __first, _ForwardIterator __last)
{ return std::is_sorted_until(__first, __last) == __last; }

/**
*  @brief  Determines whether the elements of a sequence are sorted
*          according to a comparison functor.
*  @ingroup sorting_algorithms
*  @param  __first   An iterator.
*  @param  __last    Another iterator.
*  @param  __comp    A comparison functor.
*  @return  True if the elements are sorted, false otherwise.
*/
template<typename _ForwardIterator, typename _Compare>
inline bool
is_sorted(_ForwardIterator __first, _ForwardIterator __last,
_Compare __comp)
{ return std::is_sorted_until(__first, __last, __comp) == __last; }

/**
*  @brief  Determines the end of a sorted sequence.
*  @ingroup sorting_algorithms
*  @param  __first   An iterator.
*  @param  __last    Another iterator.
*  @return  An iterator pointing to the last iterator i in [__first, __last)
*           for which the range [__first, i) is sorted.
*/
template<typename _ForwardIterator>
_ForwardIterator
is_sorted_until(_ForwardIterator __first, _ForwardIterator __last)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_LessThanComparableConcept<
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

if (__first == __last)
return __last;

_ForwardIterator __next = __first;
for (++__next; __next != __last; __first = __next, ++__next)
if (*__next < *__first)
return __next;
return __next;
}

/**
*  @brief  Determines the end of a sorted sequence using comparison functor.
*  @ingroup sorting_algorithms
*  @param  __first   An iterator.
*  @param  __last    Another iterator.
*  @param  __comp    A comparison functor.
*  @return  An iterator pointing to the last iterator i in [__first, __last)
*           for which the range [__first, i) is sorted.
*/
template<typename _ForwardIterator, typename _Compare>
_ForwardIterator
is_sorted_until(_ForwardIterator __first, _ForwardIterator __last,
_Compare __comp)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
typename iterator_traits<_ForwardIterator>::value_type,
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

if (__first == __last)
return __last;

_ForwardIterator __next = __first;
for (++__next; __next != __last; __first = __next, ++__next)
if (__comp(*__next, *__first))
return __next;
return __next;
}

/**
*  @brief  Determines min and max at once as an ordered pair.
*  @ingroup sorting_algorithms
*  @param  __a  A thing of arbitrary type.
*  @param  __b  Another thing of arbitrary type.
*  @return A pair(__b, __a) if __b is smaller than __a, pair(__a,
*  __b) otherwise.
*/
template<typename _Tp>
inline pair<const _Tp&, const _Tp&>
minmax(const _Tp& __a, const _Tp& __b)
{
// concept requirements
__glibcxx_function_requires(_LessThanComparableConcept<_Tp>)

return __b < __a ? pair<const _Tp&, const _Tp&>(__b, __a)
: pair<const _Tp&, const _Tp&>(__a, __b);
}

/**
*  @brief  Determines min and max at once as an ordered pair.
*  @ingroup sorting_algorithms
*  @param  __a  A thing of arbitrary type.
*  @param  __b  Another thing of arbitrary type.
*  @param  __comp  A @link comparison_functors comparison functor @endlink.
*  @return A pair(__b, __a) if __b is smaller than __a, pair(__a,
*  __b) otherwise.
*/
template<typename _Tp, typename _Compare>
inline pair<const _Tp&, const _Tp&>
minmax(const _Tp& __a, const _Tp& __b, _Compare __comp)
{
return __comp(__b, __a) ? pair<const _Tp&, const _Tp&>(__b, __a)
: pair<const _Tp&, const _Tp&>(__a, __b);
}

/**
*  @brief  Return a pair of iterators pointing to the minimum and maximum
*          elements in a range.
*  @ingroup sorting_algorithms
*  @param  __first  Start of range.
*  @param  __last   End of range.
*  @return  make_pair(m, M), where m is the first iterator i in
*           [__first, __last) such that no other element in the range is
*           smaller, and where M is the last iterator i in [__first, __last)
*           such that no other element in the range is larger.
*/
template<typename _ForwardIterator>
pair<_ForwardIterator, _ForwardIterator>
minmax_element(_ForwardIterator __first, _ForwardIterator __last)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_LessThanComparableConcept<
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

_ForwardIterator __next = __first;
if (__first == __last
|| ++__next == __last)
return std::make_pair(__first, __first);

_ForwardIterator __min, __max;
if (*__next < *__first)
{
__min = __next;
__max = __first;
}
else
{
__min = __first;
__max = __next;
}

__first = __next;
++__first;

while (__first != __last)
{
__next = __first;
if (++__next == __last)
{
if (*__first < *__min)
__min = __first;
else if (!(*__first < *__max))
__max = __first;
break;
}

if (*__next < *__first)
{
if (*__next < *__min)
__min = __next;
if (!(*__first < *__max))
__max = __first;
}
else
{
if (*__first < *__min)
__min = __first;
if (!(*__next < *__max))
__max = __next;
}

__first = __next;
++__first;
}

return std::make_pair(__min, __max);
}

/**
*  @brief  Return a pair of iterators pointing to the minimum and maximum
*          elements in a range.
*  @ingroup sorting_algorithms
*  @param  __first  Start of range.
*  @param  __last   End of range.
*  @param  __comp   Comparison functor.
*  @return  make_pair(m, M), where m is the first iterator i in
*           [__first, __last) such that no other element in the range is
*           smaller, and where M is the last iterator i in [__first, __last)
*           such that no other element in the range is larger.
*/
template<typename _ForwardIterator, typename _Compare>
pair<_ForwardIterator, _ForwardIterator>
minmax_element(_ForwardIterator __first, _ForwardIterator __last,
_Compare __comp)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
typename iterator_traits<_ForwardIterator>::value_type,
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

_ForwardIterator __next = __first;
if (__first == __last
|| ++__next == __last)
return std::make_pair(__first, __first);

_ForwardIterator __min, __max;
if (__comp(*__next, *__first))
{
__min = __next;
__max = __first;
}
else
{
__min = __first;
__max = __next;
}

__first = __next;
++__first;

while (__first != __last)
{
__next = __first;
if (++__next == __last)
{
if (__comp(*__first, *__min))
__min = __first;
else if (!__comp(*__first, *__max))
__max = __first;
break;
}

if (__comp(*__next, *__first))
{
if (__comp(*__next, *__min))
__min = __next;
if (!__comp(*__first, *__max))
__max = __first;
}
else
{
if (__comp(*__first, *__min))
__min = __first;
if (!__comp(*__next, *__max))
__max = __next;
}

__first = __next;
++__first;
}

return std::make_pair(__min, __max);
}

// N2722 + DR 915.
template<typename _Tp>
inline _Tp
min(initializer_list<_Tp> __l)
{ return *std::min_element(__l.begin(), __l.end()); }

template<typename _Tp, typename _Compare>
inline _Tp
min(initializer_list<_Tp> __l, _Compare __comp)
{ return *std::min_element(__l.begin(), __l.end(), __comp); }

template<typename _Tp>
inline _Tp
max(initializer_list<_Tp> __l)
{ return *std::max_element(__l.begin(), __l.end()); }

template<typename _Tp, typename _Compare>
inline _Tp
max(initializer_list<_Tp> __l, _Compare __comp)
{ return *std::max_element(__l.begin(), __l.end(), __comp); }

template<typename _Tp>
inline pair<_Tp, _Tp>
minmax(initializer_list<_Tp> __l)
{
pair<const _Tp*, const _Tp*> __p =
std::minmax_element(__l.begin(), __l.end());
return std::make_pair(*__p.first, *__p.second);
}

template<typename _Tp, typename _Compare>
inline pair<_Tp, _Tp>
minmax(initializer_list<_Tp> __l, _Compare __comp)
{
pair<const _Tp*, const _Tp*> __p =
std::minmax_element(__l.begin(), __l.end(), __comp);
return std::make_pair(*__p.first, *__p.second);
}

/**
*  @brief  Checks whether a permutaion of the second sequence is equal
*          to the first sequence.
*  @ingroup non_mutating_algorithms
*  @param  __first1  Start of first range.
*  @param  __last1   End of first range.
*  @param  __first2  Start of second range.
*  @return true if there exists a permutation of the elements in the range
*          [__first2, __first2 + (__last1 - __first1)), beginning with
*          ForwardIterator2 begin, such that equal(__first1, __last1, begin)
*          returns true; otherwise, returns false.
*/
template<typename _ForwardIterator1, typename _ForwardIterator2>
bool
is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
_ForwardIterator2 __first2)
{
// Efficiently compare identical prefixes:  O(N) if sequences
// have the same elements in the same order.
for (; __first1 != __last1; ++__first1, ++__first2)
if (!(*__first1 == *__first2))
break;

if (__first1 == __last1)
return true;

// Establish __last2 assuming equal ranges by iterating over the
// rest of the list.
_ForwardIterator2 __last2 = __first2;
std::advance(__last2, std::distance(__first1, __last1));
for (_ForwardIterator1 __scan = __first1; __scan != __last1; ++__scan)
{
if (__scan != _GLIBCXX_STD_A::find(__first1, __scan, *__scan))
continue; // We've seen this one before.

auto __matches = std::count(__first2, __last2, *__scan);
if (0 == __matches
|| std::count(__scan, __last1, *__scan) != __matches)
return false;
}
return true;
}

/**
*  @brief  Checks whether a permutation of the second sequence is equal
*          to the first sequence.
*  @ingroup non_mutating_algorithms
*  @param  __first1  Start of first range.
*  @param  __last1   End of first range.
*  @param  __first2  Start of second range.
*  @param  __pred    A binary predicate.
*  @return true if there exists a permutation of the elements in
*          the range [__first2, __first2 + (__last1 - __first1)),
*          beginning with ForwardIterator2 begin, such that
*          equal(__first1, __last1, __begin, __pred) returns true;
*          otherwise, returns false.
*/
template<typename _ForwardIterator1, typename _ForwardIterator2,
typename _BinaryPredicate>
bool
is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
_ForwardIterator2 __first2, _BinaryPredicate __pred)
{
// Efficiently compare identical prefixes:  O(N) if sequences
// have the same elements in the same order.
for (; __first1 != __last1; ++__first1, ++__first2)
if (!bool(__pred(*__first1, *__first2)))
break;

if (__first1 == __last1)
return true;

// Establish __last2 assuming equal ranges by iterating over the
// rest of the list.
_ForwardIterator2 __last2 = __first2;
std::advance(__last2, std::distance(__first1, __last1));
for (_ForwardIterator1 __scan = __first1; __scan != __last1; ++__scan)
{
using std::placeholders::_1;

if (__scan != _GLIBCXX_STD_A::find_if(__first1, __scan,
std::bind(__pred, _1, *__scan)))
continue; // We've seen this one before.

auto __matches = std::count_if(__first2, __last2,
std::bind(__pred, _1, *__scan));
if (0 == __matches
|| std::count_if(__scan, __last1,
std::bind(__pred, _1, *__scan)) != __matches)
return false;
}
return true;
}

#ifdef _GLIBCXX_USE_C99_STDINT_TR1
/**
*  @brief Shuffle the elements of a sequence using a uniform random
*         number generator.
*  @ingroup mutating_algorithms
*  @param  __first   A forward iterator.
*  @param  __last    A forward iterator.
*  @param  __g       A UniformRandomNumberGenerator (26.5.1.3).
*  @return  Nothing.
*
*  Reorders the elements in the range @p [__first,__last) using @p __g to
*  provide random numbers.
*/
template<typename _RandomAccessIterator,
typename _UniformRandomNumberGenerator>
void
shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last,
_UniformRandomNumberGenerator&& __g)
{
// concept requirements
__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
_RandomAccessIterator>)
__glibcxx_requires_valid_range(__first, __last);

if (__first == __last)
return;

typedef typename iterator_traits<_RandomAccessIterator>::difference_type
_DistanceType;

typedef typename std::make_unsigned<_DistanceType>::type __ud_type;
typedef typename std::uniform_int_distribution<__ud_type> __distr_type;
typedef typename __distr_type::param_type __p_type;
__distr_type __d;

for (_RandomAccessIterator __i = __first + 1; __i != __last; ++__i)
std::iter_swap(__i, __first + __d(__g, __p_type(0, __i - __first)));
}
#endif

#endif // __GXX_EXPERIMENTAL_CXX0X__

_GLIBCXX_END_NAMESPACE_VERSION

_GLIBCXX_BEGIN_NAMESPACE_ALGO

/**
*  @brief Apply a function to every element of a sequence.
*  @ingroup non_mutating_algorithms
*  @param  __first  An input iterator.
*  @param  __last   An input iterator.
*  @param  __f      A unary function object.
*  @return   @p __f (std::move(@p __f) in C++0x).
*
*  Applies the function object @p __f to each element in the range
*  @p [first,last).  @p __f must not modify the order of the sequence.
*  If @p __f has a return value it is ignored.
*/
template<typename _InputIterator, typename _Function>
_Function
for_each(_InputIterator __first, _InputIterator __last, _Function __f)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_requires_valid_range(__first, __last);
for (; __first != __last; ++__first)
__f(*__first);
return _GLIBCXX_MOVE(__f);
}

/**
*  @brief Find the first occurrence of a value in a sequence.
*  @ingroup non_mutating_algorithms
*  @param  __first  An input iterator.
*  @param  __last   An input iterator.
*  @param  __val    The value to find.
*  @return   The first iterator @c i in the range @p [__first,__last)
*  such that @c *i == @p __val, or @p __last if no such iterator exists.
*/
template<typename _InputIterator, typename _Tp>
inline _InputIterator
find(_InputIterator __first, _InputIterator __last,
const _Tp& __val)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_EqualOpConcept<
typename iterator_traits<_InputIterator>::value_type, _Tp>)
__glibcxx_requires_valid_range(__first, __last);
return std::__find(__first, __last, __val,
std::__iterator_category(__first));
}

/**
*  @brief Find the first element in a sequence for which a
*         predicate is true.
*  @ingroup non_mutating_algorithms
*  @param  __first  An input iterator.
*  @param  __last   An input iterator.
*  @param  __pred   A predicate.
*  @return   The first iterator @c i in the range @p [__first,__last)
*  such that @p __pred(*i) is true, or @p __last if no such iterator exists.
*/
template<typename _InputIterator, typename _Predicate>
inline _InputIterator
find_if(_InputIterator __first, _InputIterator __last,
_Predicate __pred)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
typename iterator_traits<_InputIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);
return std::__find_if(__first, __last, __pred,
std::__iterator_category(__first));
}

/**
*  @brief  Find element from a set in a sequence.
*  @ingroup non_mutating_algorithms
*  @param  __first1  Start of range to search.
*  @param  __last1   End of range to search.
*  @param  __first2  Start of match candidates.
*  @param  __last2   End of match candidates.
*  @return   The first iterator @c i in the range
*  @p [__first1,__last1) such that @c *i == @p *(i2) such that i2 is an
*  iterator in [__first2,__last2), or @p __last1 if no such iterator exists.
*
*  Searches the range @p [__first1,__last1) for an element that is
*  equal to some element in the range [__first2,__last2).  If
*  found, returns an iterator in the range [__first1,__last1),
*  otherwise returns @p __last1.
*/
template<typename _InputIterator, typename _ForwardIterator>
_InputIterator
find_first_of(_InputIterator __first1, _InputIterator __last1,
_ForwardIterator __first2, _ForwardIterator __last2)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_EqualOpConcept<
typename iterator_traits<_InputIterator>::value_type,
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first1, __last1);
__glibcxx_requires_valid_range(__first2, __last2);

for (; __first1 != __last1; ++__first1)
for (_ForwardIterator __iter = __first2; __iter != __last2; ++__iter)
if (*__first1 == *__iter)
return __first1;
return __last1;
}

/**
*  @brief  Find element from a set in a sequence using a predicate.
*  @ingroup non_mutating_algorithms
*  @param  __first1  Start of range to search.
*  @param  __last1   End of range to search.
*  @param  __first2  Start of match candidates.
*  @param  __last2   End of match candidates.
*  @param  __comp    Predicate to use.
*  @return   The first iterator @c i in the range
*  @p [__first1,__last1) such that @c comp(*i, @p *(i2)) is true
*  and i2 is an iterator in [__first2,__last2), or @p __last1 if no
*  such iterator exists.
*

*  Searches the range @p [__first1,__last1) for an element that is
*  equal to some element in the range [__first2,__last2).  If
*  found, returns an iterator in the range [__first1,__last1),
*  otherwise returns @p __last1.
*/
template<typename _InputIterator, typename _ForwardIterator,
typename _BinaryPredicate>
_InputIterator
find_first_of(_InputIterator __first1, _InputIterator __last1,
_ForwardIterator __first2, _ForwardIterator __last2,
_BinaryPredicate __comp)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
typename iterator_traits<_InputIterator>::value_type,
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first1, __last1);
__glibcxx_requires_valid_range(__first2, __last2);

for (; __first1 != __last1; ++__first1)
for (_ForwardIterator __iter = __first2; __iter != __last2; ++__iter)
if (__comp(*__first1, *__iter))
return __first1;
return __last1;
}

/**
*  @brief Find two adjacent values in a sequence that are equal.
*  @ingroup non_mutating_algorithms
*  @param  __first  A forward iterator.
*  @param  __last   A forward iterator.
*  @return   The first iterator @c i such that @c i and @c i+1 are both
*  valid iterators in @p [__first,__last) and such that @c *i == @c *(i+1),
*  or @p __last if no such iterator exists.
*/
template<typename _ForwardIterator>
_ForwardIterator
adjacent_find(_ForwardIterator __first, _ForwardIterator __last)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_EqualityComparableConcept<
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);
if (__first == __last)
return __last;
_ForwardIterator __next = __first;
while(++__next != __last)
{
if (*__first == *__next)
return __first;
__first = __next;
}
return __last;
}

/**
*  @brief Find two adjacent values in a sequence using a predicate.
*  @ingroup non_mutating_algorithms
*  @param  __first         A forward iterator.
*  @param  __last          A forward iterator.
*  @param  __binary_pred   A binary predicate.
*  @return   The first iterator @c i such that @c i and @c i+1 are both
*  valid iterators in @p [__first,__last) and such that
*  @p __binary_pred(*i,*(i+1)) is true, or @p __last if no such iterator
*  exists.
*/
template<typename _ForwardIterator, typename _BinaryPredicate>
_ForwardIterator
adjacent_find(_ForwardIterator __first, _ForwardIterator __last,
_BinaryPredicate __binary_pred)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
typename iterator_traits<_ForwardIterator>::value_type,
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);
if (__first == __last)
return __last;
_ForwardIterator __next = __first;
while(++__next != __last)
{
if (__binary_pred(*__first, *__next))
return __first;
__first = __next;
}
return __last;
}

/**
*  @brief Count the number of copies of a value in a sequence.
*  @ingroup non_mutating_algorithms
*  @param  __first  An input iterator.
*  @param  __last   An input iterator.
*  @param  __value  The value to be counted.
*  @return   The number of iterators @c i in the range @p [__first,__last)
*  for which @c *i == @p __value
*/
template<typename _InputIterator, typename _Tp>
typename iterator_traits<_InputIterator>::difference_type
count(_InputIterator __first, _InputIterator __last, const _Tp& __value)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_EqualOpConcept<
typename iterator_traits<_InputIterator>::value_type, _Tp>)
__glibcxx_requires_valid_range(__first, __last);
typename iterator_traits<_InputIterator>::difference_type __n = 0;
for (; __first != __last; ++__first)
if (*__first == __value)
++__n;
return __n;
}

/**
*  @brief Count the elements of a sequence for which a predicate is true.
*  @ingroup non_mutating_algorithms
*  @param  __first  An input iterator.
*  @param  __last   An input iterator.
*  @param  __pred   A predicate.
*  @return   The number of iterators @c i in the range @p [__first,__last)
*  for which @p __pred(*i) is true.
*/
template<typename _InputIterator, typename _Predicate>
typename iterator_traits<_InputIterator>::difference_type
count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
typename iterator_traits<_InputIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);
typename iterator_traits<_InputIterator>::difference_type __n = 0;
for (; __first != __last; ++__first)
if (__pred(*__first))
++__n;
return __n;
}

/**
*  @brief Search a sequence for a matching sub-sequence.
*  @ingroup non_mutating_algorithms
*  @param  __first1  A forward iterator.
*  @param  __last1   A forward iterator.
*  @param  __first2  A forward iterator.
*  @param  __last2   A forward iterator.
*  @return The first iterator @c i in the range @p
*  [__first1,__last1-(__last2-__first2)) such that @c *(i+N) == @p
*  *(__first2+N) for each @c N in the range @p
*  [0,__last2-__first2), or @p __last1 if no such iterator exists.
*
*  Searches the range @p [__first1,__last1) for a sub-sequence that
*  compares equal value-by-value with the sequence given by @p
*  [__first2,__last2) and returns an iterator to the first element
*  of the sub-sequence, or @p __last1 if the sub-sequence is not
*  found.
*
*  Because the sub-sequence must lie completely within the range @p
*  [__first1,__last1) it must start at a position less than @p
*  __last1-(__last2-__first2) where @p __last2-__first2 is the
*  length of the sub-sequence.
*
*  This means that the returned iterator @c i will be in the range
*  @p [__first1,__last1-(__last2-__first2))
*/
template<typename _ForwardIterator1, typename _ForwardIterator2>
_ForwardIterator1
search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
_ForwardIterator2 __first2, _ForwardIterator2 __last2)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)
__glibcxx_function_requires(_EqualOpConcept<
typename iterator_traits<_ForwardIterator1>::value_type,
typename iterator_traits<_ForwardIterator2>::value_type>)
__glibcxx_requires_valid_range(__first1, __last1);
__glibcxx_requires_valid_range(__first2, __last2);

// Test for empty ranges
if (__first1 == __last1 || __first2 == __last2)
return __first1;

// Test for a pattern of length 1.
_ForwardIterator2 __p1(__first2);
if (++__p1 == __last2)
return _GLIBCXX_STD_A::find(__first1, __last1, *__first2);

// General case.
_ForwardIterator2 __p;
_ForwardIterator1 __current = __first1;

for (;;)
{
__first1 = _GLIBCXX_STD_A::find(__first1, __last1, *__first2);
if (__first1 == __last1)
return __last1;

__p = __p1;
__current = __first1;
if (++__current == __last1)
return __last1;

while (*__current == *__p)
{
if (++__p == __last2)
return __first1;
if (++__current == __last1)
return __last1;
}
++__first1;
}
return __first1;
}

/**
*  @brief Search a sequence for a matching sub-sequence using a predicate.
*  @ingroup non_mutating_algorithms
*  @param  __first1     A forward iterator.
*  @param  __last1      A forward iterator.
*  @param  __first2     A forward iterator.
*  @param  __last2      A forward iterator.
*  @param  __predicate  A binary predicate.
*  @return   The first iterator @c i in the range
*  @p [__first1,__last1-(__last2-__first2)) such that
*  @p __predicate(*(i+N),*(__first2+N)) is true for each @c N in the range
*  @p [0,__last2-__first2), or @p __last1 if no such iterator exists.
*
*  Searches the range @p [__first1,__last1) for a sub-sequence that
*  compares equal value-by-value with the sequence given by @p
*  [__first2,__last2), using @p __predicate to determine equality,
*  and returns an iterator to the first element of the
*  sub-sequence, or @p __last1 if no such iterator exists.
*
*  @see search(_ForwardIter1, _ForwardIter1, _ForwardIter2, _ForwardIter2)
*/
template<typename _ForwardIterator1, typename _ForwardIterator2,
typename _BinaryPredicate>
_ForwardIterator1
search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
_ForwardIterator2 __first2, _ForwardIterator2 __last2,
_BinaryPredicate  __predicate)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)
__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
typename iterator_traits<_ForwardIterator1>::value_type,
typename iterator_traits<_ForwardIterator2>::value_type>)
__glibcxx_requires_valid_range(__first1, __last1);
__glibcxx_requires_valid_range(__first2, __last2);

// Test for empty ranges
if (__first1 == __last1 || __first2 == __last2)
return __first1;

// Test for a pattern of length 1.
_ForwardIterator2 __p1(__first2);
if (++__p1 == __last2)
{
while (__first1 != __last1
&& !bool(__predicate(*__first1, *__first2)))
++__first1;
return __first1;
}

// General case.
_ForwardIterator2 __p;
_ForwardIterator1 __current = __first1;

for (;;)
{
while (__first1 != __last1
&& !bool(__predicate(*__first1, *__first2)))
++__first1;
if (__first1 == __last1)
return __last1;

__p = __p1;
__current = __first1;
if (++__current == __last1)
return __last1;

while (__predicate(*__current, *__p))
{
if (++__p == __last2)
return __first1;
if (++__current == __last1)
return __last1;
}
++__first1;
}
return __first1;
}

/**
*  @brief Search a sequence for a number of consecutive values.
*  @ingroup non_mutating_algorithms
*  @param  __first  A forward iterator.
*  @param  __last   A forward iterator.
*  @param  __count  The number of consecutive values.
*  @param  __val    The value to find.
*  @return The first iterator @c i in the range @p
*  [__first,__last-__count) such that @c *(i+N) == @p __val for
*  each @c N in the range @p [0,__count), or @p __last if no such
*  iterator exists.
*
*  Searches the range @p [__first,__last) for @p count consecutive elements
*  equal to @p __val.
*/
template<typename _ForwardIterator, typename _Integer, typename _Tp>
_ForwardIterator
search_n(_ForwardIterator __first, _ForwardIterator __last,
_Integer __count, const _Tp& __val)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_EqualOpConcept<
typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
__glibcxx_requires_valid_range(__first, __last);

if (__count <= 0)
return __first;
if (__count == 1)
return _GLIBCXX_STD_A::find(__first, __last, __val);
return std::__search_n(__first, __last, __count, __val,
std::__iterator_category(__first));
}

/**
*  @brief Search a sequence for a number of consecutive values using a
*         predicate.
*  @ingroup non_mutating_algorithms
*  @param  __first        A forward iterator.
*  @param  __last         A forward iterator.
*  @param  __count        The number of consecutive values.
*  @param  __val          The value to find.
*  @param  __binary_pred  A binary predicate.
*  @return The first iterator @c i in the range @p
*  [__first,__last-__count) such that @p
*  __binary_pred(*(i+N),__val) is true for each @c N in the range
*  @p [0,__count), or @p __last if no such iterator exists.
*
*  Searches the range @p [__first,__last) for @p __count
*  consecutive elements for which the predicate returns true.
*/
template<typename _ForwardIterator, typename _Integer, typename _Tp,
typename _BinaryPredicate>
_ForwardIterator
search_n(_ForwardIterator __first, _ForwardIterator __last,
_Integer __count, const _Tp& __val,
_BinaryPredicate __binary_pred)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
__glibcxx_requires_valid_range(__first, __last);

if (__count <= 0)
return __first;
if (__count == 1)
{
while (__first != __last && !bool(__binary_pred(*__first, __val)))
++__first;
return __first;
}
return std::__search_n(__first, __last, __count, __val, __binary_pred,
std::__iterator_category(__first));
}

/**
*  @brief Perform an operation on a sequence.
*  @ingroup mutating_algorithms
*  @param  __first     An input iterator.
*  @param  __last      An input iterator.
*  @param  __result    An output iterator.
*  @param  __unary_op  A unary operator.
*  @return   An output iterator equal to @p __result+(__last-__first).
*
*  Applies the operator to each element in the input range and assigns
*  the results to successive elements of the output sequence.
*  Evaluates @p *(__result+N)=unary_op(*(__first+N)) for each @c N in the
*  range @p [0,__last-__first).
*
*  @p unary_op must not alter its argument.
*/
template<typename _InputIterator, typename _OutputIterator,
typename _UnaryOperation>
_OutputIterator
transform(_InputIterator __first, _InputIterator __last,
_OutputIterator __result, _UnaryOperation __unary_op)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
// "the type returned by a _UnaryOperation"
__typeof__(__unary_op(*__first))>)
__glibcxx_requires_valid_range(__first, __last);

for (; __first != __last; ++__first, ++__result)
*__result = __unary_op(*__first);
return __result;
}

/**
*  @brief Perform an operation on corresponding elements of two sequences.
*  @ingroup mutating_algorithms
*  @param  __first1     An input iterator.
*  @param  __last1      An input iterator.
*  @param  __first2     An input iterator.
*  @param  __result     An output iterator.
*  @param  __binary_op  A binary operator.
*  @return   An output iterator equal to @p result+(last-first).
*
*  Applies the operator to the corresponding elements in the two
*  input ranges and assigns the results to successive elements of the
*  output sequence.
*  Evaluates @p
*  *(__result+N)=__binary_op(*(__first1+N),*(__first2+N)) for each
*  @c N in the range @p [0,__last1-__first1).
*
*  @p binary_op must not alter either of its arguments.
*/
template<typename _InputIterator1, typename _InputIterator2,
typename _OutputIterator, typename _BinaryOperation>
_OutputIterator
transform(_InputIterator1 __first1, _InputIterator1 __last1,
_InputIterator2 __first2, _OutputIterator __result,
_BinaryOperation __binary_op)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
// "the type returned by a _BinaryOperation"
__typeof__(__binary_op(*__first1,*__first2))>)
__glibcxx_requires_valid_range(__first1, __last1);

for (; __first1 != __last1; ++__first1, ++__first2, ++__result)
*__result = __binary_op(*__first1, *__first2);
return __result;
}

/**
*  @brief Replace each occurrence of one value in a sequence with another
*         value.
*  @ingroup mutating_algorithms
*  @param  __first      A forward iterator.
*  @param  __last       A forward iterator.
*  @param  __old_value  The value to be replaced.
*  @param  __new_value  The replacement value.
*  @return   replace() returns no value.
*
*  For each iterator @c i in the range @p [__first,__last) if @c *i ==
*  @p __old_value then the assignment @c *i = @p __new_value is performed.
*/
template<typename _ForwardIterator, typename _Tp>
void
replace(_ForwardIterator __first, _ForwardIterator __last,
const _Tp& __old_value, const _Tp& __new_value)
{
// concept requirements
__glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
_ForwardIterator>)
__glibcxx_function_requires(_EqualOpConcept<
typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
__glibcxx_function_requires(_ConvertibleConcept<_Tp,
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

for (; __first != __last; ++__first)
if (*__first == __old_value)
*__first = __new_value;
}

/**
*  @brief Replace each value in a sequence for which a predicate returns
*         true with another value.
*  @ingroup mutating_algorithms
*  @param  __first      A forward iterator.
*  @param  __last       A forward iterator.
*  @param  __pred       A predicate.
*  @param  __new_value  The replacement value.
*  @return   replace_if() returns no value.
*
*  For each iterator @c i in the range @p [__first,__last) if @p __pred(*i)
*  is true then the assignment @c *i = @p __new_value is performed.
*/
template<typename _ForwardIterator, typename _Predicate, typename _Tp>
void
replace_if(_ForwardIterator __first, _ForwardIterator __last,
_Predicate __pred, const _Tp& __new_value)
{
// concept requirements
__glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
_ForwardIterator>)
__glibcxx_function_requires(_ConvertibleConcept<_Tp,
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

for (; __first != __last; ++__first)
if (__pred(*__first))
*__first = __new_value;
}

/**
*  @brief Assign the result of a function object to each value in a
*         sequence.
*  @ingroup mutating_algorithms
*  @param  __first  A forward iterator.
*  @param  __last   A forward iterator.
*  @param  __gen    A function object taking no arguments and returning
*                 std::iterator_traits<_ForwardIterator>::value_type
*  @return   generate() returns no value.
*
*  Performs the assignment @c *i = @p __gen() for each @c i in the range
*  @p [__first,__last).
*/
template<typename _ForwardIterator, typename _Generator>
void
generate(_ForwardIterator __first, _ForwardIterator __last,
_Generator __gen)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_GeneratorConcept<_Generator,
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

for (; __first != __last; ++__first)
*__first = __gen();
}

/**
*  @brief Assign the result of a function object to each value in a
*         sequence.
*  @ingroup mutating_algorithms
*  @param  __first  A forward iterator.
*  @param  __n      The length of the sequence.
*  @param  __gen    A function object taking no arguments and returning
*                 std::iterator_traits<_ForwardIterator>::value_type
*  @return   The end of the sequence, @p __first+__n
*
*  Performs the assignment @c *i = @p __gen() for each @c i in the range
*  @p [__first,__first+__n).
*
*  _GLIBCXX_RESOLVE_LIB_DEFECTS
*  DR 865. More algorithms that throw away information
*/
template<typename _OutputIterator, typename _Size, typename _Generator>
_OutputIterator
generate_n(_OutputIterator __first, _Size __n, _Generator __gen)
{
// concept requirements
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
// "the type returned by a _Generator"
__typeof__(__gen())>)

for (__decltype(__n + 0) __niter = __n;
__niter > 0; --__niter, ++__first)
*__first = __gen();
return __first;
}

/**
*  @brief Copy a sequence, removing consecutive duplicate values.
*  @ingroup mutating_algorithms
*  @param  __first   An input iterator.
*  @param  __last    An input iterator.
*  @param  __result  An output iterator.
*  @return   An iterator designating the end of the resulting sequence.
*
*  Copies each element in the range @p [__first,__last) to the range
*  beginning at @p __result, except that only the first element is copied
*  from groups of consecutive elements that compare equal.
*  unique_copy() is stable, so the relative order of elements that are
*  copied is unchanged.
*
*  _GLIBCXX_RESOLVE_LIB_DEFECTS
*  DR 241. Does unique_copy() require CopyConstructible and Assignable?
*
*  _GLIBCXX_RESOLVE_LIB_DEFECTS
*  DR 538. 241 again: Does unique_copy() require CopyConstructible and
*  Assignable?
*/
template<typename _InputIterator, typename _OutputIterator>
inline _OutputIterator
unique_copy(_InputIterator __first, _InputIterator __last,
_OutputIterator __result)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
typename iterator_traits<_InputIterator>::value_type>)
__glibcxx_function_requires(_EqualityComparableConcept<
typename iterator_traits<_InputIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

if (__first == __last)
return __result;
return std::__unique_copy(__first, __last, __result,
std::__iterator_category(__first),
std::__iterator_category(__result));
}

/**
*  @brief Copy a sequence, removing consecutive values using a predicate.
*  @ingroup mutating_algorithms
*  @param  __first        An input iterator.
*  @param  __last         An input iterator.
*  @param  __result       An output iterator.
*  @param  __binary_pred  A binary predicate.
*  @return   An iterator designating the end of the resulting sequence.
*
*  Copies each element in the range @p [__first,__last) to the range
*  beginning at @p __result, except that only the first element is copied
*  from groups of consecutive elements for which @p __binary_pred returns
*  true.
*  unique_copy() is stable, so the relative order of elements that are
*  copied is unchanged.
*
*  _GLIBCXX_RESOLVE_LIB_DEFECTS
*  DR 241. Does unique_copy() require CopyConstructible and Assignable?
*/
template<typename _InputIterator, typename _OutputIterator,
typename _BinaryPredicate>
inline _OutputIterator
unique_copy(_InputIterator __first, _InputIterator __last,
_OutputIterator __result,
_BinaryPredicate __binary_pred)
{
// concept requirements -- predicates checked later
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
typename iterator_traits<_InputIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

if (__first == __last)
return __result;
return std::__unique_copy(__first, __last, __result, __binary_pred,
std::__iterator_category(__first),
std::__iterator_category(__result));
}

/**
*  @brief Randomly shuffle the elements of a sequence.
*  @ingroup mutating_algorithms
*  @param  __first   A forward iterator.
*  @param  __last    A forward iterator.
*  @return  Nothing.
*
*  Reorder the elements in the range @p [__first,__last) using a random
*  distribution, so that every possible ordering of the sequence is
*  equally likely.
*/
template<typename _RandomAccessIterator>
inline void
random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last)
{
// concept requirements
__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
_RandomAccessIterator>)
__glibcxx_requires_valid_range(__first, __last);

if (__first != __last)
for (_RandomAccessIterator __i = __first + 1; __i != __last; ++__i)
std::iter_swap(__i, __first + (std::rand() % ((__i - __first) + 1)));
}

/**
*  @brief Shuffle the elements of a sequence using a random number
*         generator.
*  @ingroup mutating_algorithms
*  @param  __first   A forward iterator.
*  @param  __last    A forward iterator.
*  @param  __rand    The RNG functor or function.
*  @return  Nothing.
*
*  Reorders the elements in the range @p [__first,__last) using @p __rand to
*  provide a random distribution. Calling @p __rand(N) for a positive
*  integer @p N should return a randomly chosen integer from the
*  range [0,N).
*/
template<typename _RandomAccessIterator, typename _RandomNumberGenerator>
void
random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last,
#ifdef __GXX_EXPERIMENTAL_CXX0X__
_RandomNumberGenerator&& __rand)
#else
_RandomNumberGenerator& __rand)
#endif
{
// concept requirements
__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
_RandomAccessIterator>)
__glibcxx_requires_valid_range(__first, __last);

if (__first == __last)
return;
for (_RandomAccessIterator __i = __first + 1; __i != __last; ++__i)
std::iter_swap(__i, __first + __rand((__i - __first) + 1));
}

/**
*  @brief Move elements for which a predicate is true to the beginning
*         of a sequence.
*  @ingroup mutating_algorithms
*  @param  __first   A forward iterator.
*  @param  __last    A forward iterator.
*  @param  __pred    A predicate functor.
*  @return  An iterator @p middle such that @p __pred(i) is true for each
*  iterator @p i in the range @p [__first,middle) and false for each @p i
*  in the range @p [middle,__last).
*
*  @p __pred must not modify its operand. @p partition() does not preserve
*  the relative ordering of elements in each group, use
*  @p stable_partition() if this is needed.
*/
template<typename _ForwardIterator, typename _Predicate>
inline _ForwardIterator
partition(_ForwardIterator __first, _ForwardIterator __last,
_Predicate   __pred)
{
// concept requirements
__glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
_ForwardIterator>)
__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

return std::__partition(__first, __last, __pred,
std::__iterator_category(__first));
}

/**
*  @brief Sort the smallest elements of a sequence.
*  @ingroup sorting_algorithms
*  @param  __first   An iterator.
*  @param  __middle  Another iterator.
*  @param  __last    Another iterator.
*  @return  Nothing.
*
*  Sorts the smallest @p (__middle-__first) elements in the range
*  @p [first,last) and moves them to the range @p [__first,__middle). The
*  order of the remaining elements in the range @p [__middle,__last) is
*  undefined.
*  After the sort if @e i and @e j are iterators in the range
*  @p [__first,__middle) such that i precedes j and @e k is an iterator in
*  the range @p [__middle,__last) then *j<*i and *k<*i are both false.
*/
template<typename _RandomAccessIterator>
inline void
partial_sort(_RandomAccessIterator __first,
_RandomAccessIterator __middle,
_RandomAccessIterator __last)
{
typedef typename iterator_traits<_RandomAccessIterator>::value_type
_ValueType;

// concept requirements
__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
_RandomAccessIterator>)
__glibcxx_function_requires(_LessThanComparableConcept<_ValueType>)
__glibcxx_requires_valid_range(__first, __middle);
__glibcxx_requires_valid_range(__middle, __last);

std::__heap_select(__first, __middle, __last);
std::sort_heap(__first, __middle);
}

/**
*  @brief Sort the smallest elements of a sequence using a predicate
*         for comparison.
*  @ingroup sorting_algorithms
*  @param  __first   An iterator.
*  @param  __middle  Another iterator.
*  @param  __last    Another iterator.
*  @param  __comp    A comparison functor.
*  @return  Nothing.
*
*  Sorts the smallest @p (__middle-__first) elements in the range
*  @p [__first,__last) and moves them to the range @p [__first,__middle). The
*  order of the remaining elements in the range @p [__middle,__last) is
*  undefined.
*  After the sort if @e i and @e j are iterators in the range
*  @p [__first,__middle) such that i precedes j and @e k is an iterator in
*  the range @p [__middle,__last) then @p *__comp(j,*i) and @p __comp(*k,*i)
*  are both false.
*/
template<typename _RandomAccessIterator, typename _Compare>
inline void
partial_sort(_RandomAccessIterator __first,
_RandomAccessIterator __middle,
_RandomAccessIterator __last,
_Compare __comp)
{
typedef typename iterator_traits<_RandomAccessIterator>::value_type
_ValueType;

// concept requirements
__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
_RandomAccessIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_ValueType, _ValueType>)
__glibcxx_requires_valid_range(__first, __middle);
__glibcxx_requires_valid_range(__middle, __last);

std::__heap_select(__first, __middle, __last, __comp);
std::sort_heap(__first, __middle, __comp);
}

/**
*  @brief Sort a sequence just enough to find a particular position.
*  @ingroup sorting_algorithms
*  @param  __first   An iterator.
*  @param  __nth     Another iterator.
*  @param  __last    Another iterator.
*  @return  Nothing.
*
*  Rearranges the elements in the range @p [__first,__last) so that @p *__nth
*  is the same element that would have been in that position had the
*  whole sequence been sorted. The elements either side of @p *__nth are
*  not completely sorted, but for any iterator @e i in the range
*  @p [__first,__nth) and any iterator @e j in the range @p [__nth,__last) it
*  holds that *j < *i is false.
*/
template<typename _RandomAccessIterator>
inline void
nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth,
_RandomAccessIterator __last)
{
typedef typename iterator_traits<_RandomAccessIterator>::value_type
_ValueType;

// concept requirements
__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
_RandomAccessIterator>)
__glibcxx_function_requires(_LessThanComparableConcept<_ValueType>)
__glibcxx_requires_valid_range(__first, __nth);
__glibcxx_requires_valid_range(__nth, __last);

if (__first == __last || __nth == __last)
return;

std::__introselect(__first, __nth, __last,
std::__lg(__last - __first) * 2);
}

/**
*  @brief Sort a sequence just enough to find a particular position
*         using a predicate for comparison.
*  @ingroup sorting_algorithms
*  @param  __first   An iterator.
*  @param  __nth     Another iterator.
*  @param  __last    Another iterator.
*  @param  __comp    A comparison functor.
*  @return  Nothing.
*
*  Rearranges the elements in the range @p [__first,__last) so that @p *__nth
*  is the same element that would have been in that position had the
*  whole sequence been sorted. The elements either side of @p *__nth are
*  not completely sorted, but for any iterator @e i in the range
*  @p [__first,__nth) and any iterator @e j in the range @p [__nth,__last) it
*  holds that @p __comp(*j,*i) is false.
*/
template<typename _RandomAccessIterator, typename _Compare>
inline void
nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth,
_RandomAccessIterator __last, _Compare __comp)
{
typedef typename iterator_traits<_RandomAccessIterator>::value_type
_ValueType;

// concept requirements
__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
_RandomAccessIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_ValueType, _ValueType>)
__glibcxx_requires_valid_range(__first, __nth);
__glibcxx_requires_valid_range(__nth, __last);

if (__first == __last || __nth == __last)
return;

std::__introselect(__first, __nth, __last,
std::__lg(__last - __first) * 2, __comp);
}

/**
*  @brief Sort the elements of a sequence.
*  @ingroup sorting_algorithms
*  @param  __first   An iterator.
*  @param  __last    Another iterator.
*  @return  Nothing.
*
*  Sorts the elements in the range @p [__first,__last) in ascending order,
*  such that for each iterator @e i in the range @p [__first,__last-1),
*  *(i+1)<*i is false.
*
*  The relative ordering of equivalent elements is not preserved, use
*  @p stable_sort() if this is needed.
*/
template<typename _RandomAccessIterator>
inline void
sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
{
typedef typename iterator_traits<_RandomAccessIterator>::value_type
_ValueType;

// concept requirements
__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
_RandomAccessIterator>)
__glibcxx_function_requires(_LessThanComparableConcept<_ValueType>)
__glibcxx_requires_valid_range(__first, __last);

if (__first != __last)
{
std::__introsort_loop(__first, __last,
std::__lg(__last - __first) * 2);
std::__final_insertion_sort(__first, __last);
}
}

/**
*  @brief Sort the elements of a sequence using a predicate for comparison.
*  @ingroup sorting_algorithms
*  @param  __first   An iterator.
*  @param  __last    Another iterator.
*  @param  __comp    A comparison functor.
*  @return  Nothing.
*
*  Sorts the elements in the range @p [__first,__last) in ascending order,
*  such that @p __comp(*(i+1),*i) is false for every iterator @e i in the
*  range @p [__first,__last-1).
*
*  The relative ordering of equivalent elements is not preserved, use
*  @p stable_sort() if this is needed.
*/
template<typename _RandomAccessIterator, typename _Compare>
inline void
sort(_RandomAccessIterator __first, _RandomAccessIterator __last,
_Compare __comp)
{
typedef typename iterator_traits<_RandomAccessIterator>::value_type
_ValueType;

// concept requirements
__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
_RandomAccessIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare, _ValueType,
_ValueType>)
__glibcxx_requires_valid_range(__first, __last);

if (__first != __last)
{
std::__introsort_loop(__first, __last,
std::__lg(__last - __first) * 2, __comp);
std::__final_insertion_sort(__first, __last, __comp);
}
}

/**
*  @brief Merges two sorted ranges.
*  @ingroup sorting_algorithms
*  @param  __first1  An iterator.
*  @param  __first2  Another iterator.
*  @param  __last1   Another iterator.
*  @param  __last2   Another iterator.
*  @param  __result  An iterator pointing to the end of the merged range.
*  @return         An iterator pointing to the first element <em>not less
*                  than</em> @e val.
*
*  Merges the ranges @p [__first1,__last1) and @p [__first2,__last2) into
*  the sorted range @p [__result, __result + (__last1-__first1) +
*  (__last2-__first2)).  Both input ranges must be sorted, and the
*  output range must not overlap with either of the input ranges.
*  The sort is @e stable, that is, for equivalent elements in the
*  two ranges, elements from the first range will always come
*  before elements from the second.
*/
template<typename _InputIterator1, typename _InputIterator2,
typename _OutputIterator>
_OutputIterator
merge(_InputIterator1 __first1, _InputIterator1 __last1,
_InputIterator2 __first2, _InputIterator2 __last2,
_OutputIterator __result)
{
typedef typename iterator_traits<_InputIterator1>::value_type
_ValueType1;
typedef typename iterator_traits<_InputIterator2>::value_type
_ValueType2;

// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
_ValueType1>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
_ValueType2>)
__glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
__glibcxx_requires_sorted_set(__first1, __last1, __first2);
__glibcxx_requires_sorted_set(__first2, __last2, __first1);

while (__first1 != __last1 && __first2 != __last2)
{
if (*__first2 < *__first1)
{
*__result = *__first2;
++__first2;
}
else
{
*__result = *__first1;
++__first1;
}
++__result;
}
return std::copy(__first2, __last2, std::copy(__first1, __last1,
__result));
}

/**
*  @brief Merges two sorted ranges.
*  @ingroup sorting_algorithms
*  @param  __first1  An iterator.
*  @param  __first2  Another iterator.
*  @param  __last1   Another iterator.
*  @param  __last2   Another iterator.
*  @param  __result  An iterator pointing to the end of the merged range.
*  @param  __comp    A functor to use for comparisons.
*  @return         An iterator pointing to the first element "not less
*                  than" @e val.
*
*  Merges the ranges @p [__first1,__last1) and @p [__first2,__last2) into
*  the sorted range @p [__result, __result + (__last1-__first1) +
*  (__last2-__first2)).  Both input ranges must be sorted, and the
*  output range must not overlap with either of the input ranges.
*  The sort is @e stable, that is, for equivalent elements in the
*  two ranges, elements from the first range will always come
*  before elements from the second.
*
*  The comparison function should have the same effects on ordering as
*  the function used for the initial sort.
*/
template<typename _InputIterator1, typename _InputIterator2,
typename _OutputIterator, typename _Compare>
_OutputIterator
merge(_InputIterator1 __first1, _InputIterator1 __last1,
_InputIterator2 __first2, _InputIterator2 __last2,
_OutputIterator __result, _Compare __comp)
{
typedef typename iterator_traits<_InputIterator1>::value_type
_ValueType1;
typedef typename iterator_traits<_InputIterator2>::value_type
_ValueType2;

// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
_ValueType1>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
_ValueType2>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_ValueType2, _ValueType1>)
__glibcxx_requires_sorted_set_pred(__first1, __last1, __first2, __comp);
__glibcxx_requires_sorted_set_pred(__first2, __last2, __first1, __comp);

while (__first1 != __last1 && __first2 != __last2)
{
if (__comp(*__first2, *__first1))
{
*__result = *__first2;
++__first2;
}
else
{
*__result = *__first1;
++__first1;
}
++__result;
}
return std::copy(__first2, __last2, std::copy(__first1, __last1,
__result));
}

/**
*  @brief Sort the elements of a sequence, preserving the relative order
*         of equivalent elements.
*  @ingroup sorting_algorithms
*  @param  __first   An iterator.
*  @param  __last    Another iterator.
*  @return  Nothing.
*
*  Sorts the elements in the range @p [__first,__last) in ascending order,
*  such that for each iterator @p i in the range @p [__first,__last-1),
*  @p *(i+1)<*i is false.
*
*  The relative ordering of equivalent elements is preserved, so any two
*  elements @p x and @p y in the range @p [__first,__last) such that
*  @p x<y is false and @p y<x is false will have the same relative
*  ordering after calling @p stable_sort().
*/
template<typename _RandomAccessIterator>
inline void
stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
{
typedef typename iterator_traits<_RandomAccessIterator>::value_type
_ValueType;
typedef typename iterator_traits<_RandomAccessIterator>::difference_type
_DistanceType;

// concept requirements
__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
_RandomAccessIterator>)
__glibcxx_function_requires(_LessThanComparableConcept<_ValueType>)
__glibcxx_requires_valid_range(__first, __last);

_Temporary_buffer<_RandomAccessIterator, _ValueType> __buf(__first,
__last);
if (__buf.begin() == 0)
std::__inplace_stable_sort(__first, __last);
else
std::__stable_sort_adaptive(__first, __last, __buf.begin(),
_DistanceType(__buf.size()));
}

/**
*  @brief Sort the elements of a sequence using a predicate for comparison,
*         preserving the relative order of equivalent elements.
*  @ingroup sorting_algorithms
*  @param  __first   An iterator.
*  @param  __last    Another iterator.
*  @param  __comp    A comparison functor.
*  @return  Nothing.
*
*  Sorts the elements in the range @p [__first,__last) in ascending order,
*  such that for each iterator @p i in the range @p [__first,__last-1),
*  @p __comp(*(i+1),*i) is false.
*
*  The relative ordering of equivalent elements is preserved, so any two
*  elements @p x and @p y in the range @p [__first,__last) such that
*  @p __comp(x,y) is false and @p __comp(y,x) is false will have the same
*  relative ordering after calling @p stable_sort().
*/
template<typename _RandomAccessIterator, typename _Compare>
inline void
stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last,
_Compare __comp)
{
typedef typename iterator_traits<_RandomAccessIterator>::value_type
_ValueType;
typedef typename iterator_traits<_RandomAccessIterator>::difference_type
_DistanceType;

// concept requirements
__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
_RandomAccessIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_ValueType,
_ValueType>)
__glibcxx_requires_valid_range(__first, __last);

_Temporary_buffer<_RandomAccessIterator, _ValueType> __buf(__first,
__last);
if (__buf.begin() == 0)
std::__inplace_stable_sort(__first, __last, __comp);
else
std::__stable_sort_adaptive(__first, __last, __buf.begin(),
_DistanceType(__buf.size()), __comp);
}

/**
*  @brief Return the union of two sorted ranges.
*  @ingroup set_algorithms
*  @param  __first1  Start of first range.
*  @param  __last1   End of first range.
*  @param  __first2  Start of second range.
*  @param  __last2   End of second range.
*  @return  End of the output range.
*  @ingroup set_algorithms
*
*  This operation iterates over both ranges, copying elements present in
*  each range in order to the output range.  Iterators increment for each
*  range.  When the current element of one range is less than the other,
*  that element is copied and the iterator advanced.  If an element is
*  contained in both ranges, the element from the first range is copied and
*  both ranges advance.  The output range may not overlap either input
*  range.
*/
template<typename _InputIterator1, typename _InputIterator2,
typename _OutputIterator>
_OutputIterator
set_union(_InputIterator1 __first1, _InputIterator1 __last1,
_InputIterator2 __first2, _InputIterator2 __last2,
_OutputIterator __result)
{
typedef typename iterator_traits<_InputIterator1>::value_type
_ValueType1;
typedef typename iterator_traits<_InputIterator2>::value_type
_ValueType2;

// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
_ValueType1>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
_ValueType2>)
__glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
__glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
__glibcxx_requires_sorted_set(__first1, __last1, __first2);
__glibcxx_requires_sorted_set(__first2, __last2, __first1);

while (__first1 != __last1 && __first2 != __last2)
{
if (*__first1 < *__first2)
{
*__result = *__first1;
++__first1;
}
else if (*__first2 < *__first1)
{
*__result = *__first2;
++__first2;
}
else
{
*__result = *__first1;
++__first1;
++__first2;
}
++__result;
}
return std::copy(__first2, __last2, std::copy(__first1, __last1,
__result));
}

/**
*  @brief Return the union of two sorted ranges using a comparison functor.
*  @ingroup set_algorithms
*  @param  __first1  Start of first range.
*  @param  __last1   End of first range.
*  @param  __first2  Start of second range.
*  @param  __last2   End of second range.
*  @param  __comp    The comparison functor.
*  @return  End of the output range.
*  @ingroup set_algorithms
*
*  This operation iterates over both ranges, copying elements present in
*  each range in order to the output range.  Iterators increment for each
*  range.  When the current element of one range is less than the other
*  according to @p __comp, that element is copied and the iterator advanced.
*  If an equivalent element according to @p __comp is contained in both
*  ranges, the element from the first range is copied and both ranges
*  advance.  The output range may not overlap either input range.
*/
template<typename _InputIterator1, typename _InputIterator2,
typename _OutputIterator, typename _Compare>
_OutputIterator
set_union(_InputIterator1 __first1, _InputIterator1 __last1,
_InputIterator2 __first2, _InputIterator2 __last2,
_OutputIterator __result, _Compare __comp)
{
typedef typename iterator_traits<_InputIterator1>::value_type
_ValueType1;
typedef typename iterator_traits<_InputIterator2>::value_type
_ValueType2;

// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
_ValueType1>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
_ValueType2>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_ValueType1, _ValueType2>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_ValueType2, _ValueType1>)
__glibcxx_requires_sorted_set_pred(__first1, __last1, __first2, __comp);
__glibcxx_requires_sorted_set_pred(__first2, __last2, __first1, __comp);

while (__first1 != __last1 && __first2 != __last2)
{
if (__comp(*__first1, *__first2))
{
*__result = *__first1;
++__first1;
}
else if (__comp(*__first2, *__first1))
{
*__result = *__first2;
++__first2;
}
else
{
*__result = *__first1;
++__first1;
++__first2;
}
++__result;
}
return std::copy(__first2, __last2, std::copy(__first1, __last1,
__result));
}

/**
*  @brief Return the intersection of two sorted ranges.
*  @ingroup set_algorithms
*  @param  __first1  Start of first range.
*  @param  __last1   End of first range.
*  @param  __first2  Start of second range.
*  @param  __last2   End of second range.
*  @return  End of the output range.
*  @ingroup set_algorithms
*
*  This operation iterates over both ranges, copying elements present in
*  both ranges in order to the output range.  Iterators increment for each
*  range.  When the current element of one range is less than the other,
*  that iterator advances.  If an element is contained in both ranges, the
*  element from the first range is copied and both ranges advance.  The
*  output range may not overlap either input range.
*/
template<typename _InputIterator1, typename _InputIterator2,
typename _OutputIterator>
_OutputIterator
set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
_InputIterator2 __first2, _InputIterator2 __last2,
_OutputIterator __result)
{
typedef typename iterator_traits<_InputIterator1>::value_type
_ValueType1;
typedef typename iterator_traits<_InputIterator2>::value_type
_ValueType2;

// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
_ValueType1>)
__glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
__glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
__glibcxx_requires_sorted_set(__first1, __last1, __first2);
__glibcxx_requires_sorted_set(__first2, __last2, __first1);

while (__first1 != __last1 && __first2 != __last2)
if (*__first1 < *__first2)
++__first1;
else if (*__first2 < *__first1)
++__first2;
else
{
*__result = *__first1;
++__first1;
++__first2;
++__result;
}
return __result;
}

/**
*  @brief Return the intersection of two sorted ranges using comparison
*  functor.
*  @ingroup set_algorithms
*  @param  __first1  Start of first range.
*  @param  __last1   End of first range.
*  @param  __first2  Start of second range.
*  @param  __last2   End of second range.
*  @param  __comp    The comparison functor.
*  @return  End of the output range.
*  @ingroup set_algorithms
*
*  This operation iterates over both ranges, copying elements present in
*  both ranges in order to the output range.  Iterators increment for each
*  range.  When the current element of one range is less than the other
*  according to @p __comp, that iterator advances.  If an element is
*  contained in both ranges according to @p __comp, the element from the
*  first range is copied and both ranges advance.  The output range may not
*  overlap either input range.
*/
template<typename _InputIterator1, typename _InputIterator2,
typename _OutputIterator, typename _Compare>
_OutputIterator
set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
_InputIterator2 __first2, _InputIterator2 __last2,
_OutputIterator __result, _Compare __comp)
{
typedef typename iterator_traits<_InputIterator1>::value_type
_ValueType1;
typedef typename iterator_traits<_InputIterator2>::value_type
_ValueType2;

// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
_ValueType1>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_ValueType1, _ValueType2>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_ValueType2, _ValueType1>)
__glibcxx_requires_sorted_set_pred(__first1, __last1, __first2, __comp);
__glibcxx_requires_sorted_set_pred(__first2, __last2, __first1, __comp);

while (__first1 != __last1 && __first2 != __last2)
if (__comp(*__first1, *__first2))
++__first1;
else if (__comp(*__first2, *__first1))
++__first2;
else
{
*__result = *__first1;
++__first1;
++__first2;
++__result;
}
return __result;
}

/**
*  @brief Return the difference of two sorted ranges.
*  @ingroup set_algorithms
*  @param  __first1  Start of first range.
*  @param  __last1   End of first range.
*  @param  __first2  Start of second range.
*  @param  __last2   End of second range.
*  @return  End of the output range.
*  @ingroup set_algorithms
*
*  This operation iterates over both ranges, copying elements present in
*  the first range but not the second in order to the output range.
*  Iterators increment for each range.  When the current element of the
*  first range is less than the second, that element is copied and the
*  iterator advances.  If the current element of the second range is less,
*  the iterator advances, but no element is copied.  If an element is
*  contained in both ranges, no elements are copied and both ranges
*  advance.  The output range may not overlap either input range.
*/
template<typename _InputIterator1, typename _InputIterator2,
typename _OutputIterator>
_OutputIterator
set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
_InputIterator2 __first2, _InputIterator2 __last2,
_OutputIterator __result)
{
typedef typename iterator_traits<_InputIterator1>::value_type
_ValueType1;
typedef typename iterator_traits<_InputIterator2>::value_type
_ValueType2;

// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
_ValueType1>)
__glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
__glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
__glibcxx_requires_sorted_set(__first1, __last1, __first2);
__glibcxx_requires_sorted_set(__first2, __last2, __first1);

while (__first1 != __last1 && __first2 != __last2)
if (*__first1 < *__first2)
{
*__result = *__first1;
++__first1;
++__result;
}
else if (*__first2 < *__first1)
++__first2;
else
{
++__first1;
++__first2;
}
return std::copy(__first1, __last1, __result);
}

/**
*  @brief  Return the difference of two sorted ranges using comparison
*  functor.
*  @ingroup set_algorithms
*  @param  __first1  Start of first range.
*  @param  __last1   End of first range.
*  @param  __first2  Start of second range.
*  @param  __last2   End of second range.
*  @param  __comp    The comparison functor.
*  @return  End of the output range.
*  @ingroup set_algorithms
*
*  This operation iterates over both ranges, copying elements present in
*  the first range but not the second in order to the output range.
*  Iterators increment for each range.  When the current element of the
*  first range is less than the second according to @p __comp, that element
*  is copied and the iterator advances.  If the current element of the
*  second range is less, no element is copied and the iterator advances.
*  If an element is contained in both ranges according to @p __comp, no
*  elements are copied and both ranges advance.  The output range may not
*  overlap either input range.
*/
template<typename _InputIterator1, typename _InputIterator2,
typename _OutputIterator, typename _Compare>
_OutputIterator
set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
_InputIterator2 __first2, _InputIterator2 __last2,
_OutputIterator __result, _Compare __comp)
{
typedef typename iterator_traits<_InputIterator1>::value_type
_ValueType1;
typedef typename iterator_traits<_InputIterator2>::value_type
_ValueType2;

// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
_ValueType1>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_ValueType1, _ValueType2>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_ValueType2, _ValueType1>)
__glibcxx_requires_sorted_set_pred(__first1, __last1, __first2, __comp);
__glibcxx_requires_sorted_set_pred(__first2, __last2, __first1, __comp);

while (__first1 != __last1 && __first2 != __last2)
if (__comp(*__first1, *__first2))
{
*__result = *__first1;
++__first1;
++__result;
}
else if (__comp(*__first2, *__first1))
++__first2;
else
{
++__first1;
++__first2;
}
return std::copy(__first1, __last1, __result);
}

/**
*  @brief  Return the symmetric difference of two sorted ranges.
*  @ingroup set_algorithms
*  @param  __first1  Start of first range.
*  @param  __last1   End of first range.
*  @param  __first2  Start of second range.
*  @param  __last2   End of second range.
*  @return  End of the output range.
*  @ingroup set_algorithms
*
*  This operation iterates over both ranges, copying elements present in
*  one range but not the other in order to the output range.  Iterators
*  increment for each range.  When the current element of one range is less
*  than the other, that element is copied and the iterator advances.  If an
*  element is contained in both ranges, no elements are copied and both
*  ranges advance.  The output range may not overlap either input range.
*/
template<typename _InputIterator1, typename _InputIterator2,
typename _OutputIterator>
_OutputIterator
set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
_InputIterator2 __first2, _InputIterator2 __last2,
_OutputIterator __result)
{
typedef typename iterator_traits<_InputIterator1>::value_type
_ValueType1;
typedef typename iterator_traits<_InputIterator2>::value_type
_ValueType2;

// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
_ValueType1>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
_ValueType2>)
__glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
__glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
__glibcxx_requires_sorted_set(__first1, __last1, __first2);
__glibcxx_requires_sorted_set(__first2, __last2, __first1);

while (__first1 != __last1 && __first2 != __last2)
if (*__first1 < *__first2)
{
*__result = *__first1;
++__first1;
++__result;
}
else if (*__first2 < *__first1)
{
*__result = *__first2;
++__first2;
++__result;
}
else
{
++__first1;
++__first2;
}
return std::copy(__first2, __last2, std::copy(__first1,
__last1, __result));
}

/**
*  @brief  Return the symmetric difference of two sorted ranges using
*  comparison functor.
*  @ingroup set_algorithms
*  @param  __first1  Start of first range.
*  @param  __last1   End of first range.
*  @param  __first2  Start of second range.
*  @param  __last2   End of second range.
*  @param  __comp    The comparison functor.
*  @return  End of the output range.
*  @ingroup set_algorithms
*
*  This operation iterates over both ranges, copying elements present in
*  one range but not the other in order to the output range.  Iterators
*  increment for each range.  When the current element of one range is less
*  than the other according to @p comp, that element is copied and the
*  iterator advances.  If an element is contained in both ranges according
*  to @p __comp, no elements are copied and both ranges advance.  The output
*  range may not overlap either input range.
*/
template<typename _InputIterator1, typename _InputIterator2,
typename _OutputIterator, typename _Compare>
_OutputIterator
set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
_InputIterator2 __first2, _InputIterator2 __last2,
_OutputIterator __result,
_Compare __comp)
{
typedef typename iterator_traits<_InputIterator1>::value_type
_ValueType1;
typedef typename iterator_traits<_InputIterator2>::value_type
_ValueType2;

// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
_ValueType1>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
_ValueType2>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_ValueType1, _ValueType2>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
_ValueType2, _ValueType1>)
__glibcxx_requires_sorted_set_pred(__first1, __last1, __first2, __comp);
__glibcxx_requires_sorted_set_pred(__first2, __last2, __first1, __comp);

while (__first1 != __last1 && __first2 != __last2)
if (__comp(*__first1, *__first2))
{
*__result = *__first1;
++__first1;
++__result;
}
else if (__comp(*__first2, *__first1))
{
*__result = *__first2;
++__first2;
++__result;
}
else
{
++__first1;
++__first2;
}
return std::copy(__first2, __last2,
std::copy(__first1, __last1, __result));
}

/**
*  @brief  Return the minimum element in a range.
*  @ingroup sorting_algorithms
*  @param  __first  Start of range.
*  @param  __last   End of range.
*  @return  Iterator referencing the first instance of the smallest value.
*/
template<typename _ForwardIterator>
_ForwardIterator
min_element(_ForwardIterator __first, _ForwardIterator __last)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_LessThanComparableConcept<
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

if (__first == __last)
return __first;
_ForwardIterator __result = __first;
while (++__first != __last)
if (*__first < *__result)
__result = __first;
return __result;
}

/**
*  @brief  Return the minimum element in a range using comparison functor.
*  @ingroup sorting_algorithms
*  @param  __first  Start of range.
*  @param  __last   End of range.
*  @param  __comp   Comparison functor.
*  @return  Iterator referencing the first instance of the smallest value
*  according to __comp.
*/
template<typename _ForwardIterator, typename _Compare>
_ForwardIterator
min_element(_ForwardIterator __first, _ForwardIterator __last,
_Compare __comp)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
typename iterator_traits<_ForwardIterator>::value_type,
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

if (__first == __last)
return __first;
_ForwardIterator __result = __first;
while (++__first != __last)
if (__comp(*__first, *__result))
__result = __first;
return __result;
}

/**
*  @brief  Return the maximum element in a range.
*  @ingroup sorting_algorithms
*  @param  __first  Start of range.
*  @param  __last   End of range.
*  @return  Iterator referencing the first instance of the largest value.
*/
template<typename _ForwardIterator>
_ForwardIterator
max_element(_ForwardIterator __first, _ForwardIterator __last)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_LessThanComparableConcept<
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

if (__first == __last)
return __first;
_ForwardIterator __result = __first;
while (++__first != __last)
if (*__result < *__first)
__result = __first;
return __result;
}

/**
*  @brief  Return the maximum element in a range using comparison functor.
*  @ingroup sorting_algorithms
*  @param  __first  Start of range.
*  @param  __last   End of range.
*  @param  __comp   Comparison functor.
*  @return  Iterator referencing the first instance of the largest value
*  according to __comp.
*/
template<typename _ForwardIterator, typename _Compare>
_ForwardIterator
max_element(_ForwardIterator __first, _ForwardIterator __last,
_Compare __comp)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
typename iterator_traits<_ForwardIterator>::value_type,
typename iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);

if (__first == __last) return __first;
_ForwardIterator __result = __first;
while (++__first != __last)
if (__comp(*__result, *__first))
__result = __first;
return __result;
}

_GLIBCXX_END_NAMESPACE_ALGO
} // namespace std

#endif /* _STL_ALGO_H */
</span>