用两种方法实现栈---顺序表和链表

栈是一种先进后出的数据结构，栈中的数据是先进后出的（First In Last Out, FILO）。栈只有一个出口，允许新增元素（只能在栈顶上增加）、移出元素（只能移出栈顶元素）、取得栈顶元素等操作。在STL中，栈是以别的容器作为底部结构，再将接口改变，使之符合栈的特性就可以了。栈里面常用的函数有push()（增）,pop()（删）,size()（求大小）,top()（顶部）和empty()（空），

下面是用顺序表实现栈的各种函数



顺序表代码实现：#include <iostream>
#include <assert.h>
using namespace std;

template<typename T>
class Stack
{
public:
Stack()
:_a(NULL)
, _top(0)
, _capacity(0)
{}

~Stack()
{
if (_a)
{
delete[] _a;
}
}

public:

void _CheckCapacity()
{
if (_a == NULL)
{
_capacity = 3;
_a = new T[_capacity];
return;
}

if (_top == _capacity)
{
_capacity *= 2;
T* tmp = new T[_capacity];
for (size_t i = 0; i < _top; i++)
{
tmp[i] = _a[i];
}

delete[] _a;
_a = tmp;
}

}

void Push(const T& x)
{
_CheckCapacity();
_a[_top++] = x;
}

void Pop()
{
assert(_top > 0);
--_top;
}

size_t Size()
{
return _top;
}

bool Empty()
{
return _top == 0;
}

T& Top()
{
return _a[_top];
}

private:
T* _a;
size_t _top;
size_t _capacity;
};

链表实现栈：



链表实现代码：

#include <iostream>
#include <assert.h>
using namespace std;

template<typename T>
struct Node
{
Node(const T& x)
:_data(x)
,_next(NULL)
{}

T _data;
Node<T>* _next;
};

template<typename T>
class Stack
{
public:
Stack()
:_top(NULL)
,_base(NULL)
,_size(0)
{}

~Stack()
{}

void Push(const T& x)
{
if (_top == NULL)
{
_top = new Node<T>(x);
_base = _top;
}
else
{

_top->_next = new Node<T>(x);
_top = _top->_next;
}
++_size;
}

void Pop()
{
assert(_top);

Node<T>* cur = _base;

while (cur->_next != _top)
{
if (cur == NULL)
{
printf("Stack is empty!\n");
return;
}
cur = cur->_next;
}

delete _top;
_top = cur;
--_size;
}

T& Top()
{
return _top->_data;
}
bool Empty()
{
return _top == NULL;
}
size_t Size()
{
return _size;
}

private:
Node<T>* _top;
Node<T>* _base;
size_t _size;
};

测试代码：

test.cppvoid Test()
{
Stack<int> s1;
s1.Push(0);
s1.Push(1);
s1.Push(2);
s1.Push(3);
s1.Push(4);
s1.Push(5);

s1.Pop();
s1.Pop();
s1.Pop();

int top = s1.Top();
size_t size = s1.Size();
cout << s1.Empty() << endl;

}

int main()
{
Test();
system("pause");
return 0;
}