leetCode(55):Minimum Window Substring（limits.h头文件）

Given a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n).

For example,

S =

"ADOBECODEBANC"

T =

"ABC"

Minimum window is

"BANC"

.

Note:

If there is no such window in S that covers all characters in T, return the emtpy string

""

.

If there are multiple such windows, you are guaranteed that there will always be only one unique minimum window in S.

不会做，看了别人的程序，自己按他的思路写了个。当作学学别人的编程技巧了。

class Solution {
public:
    string minWindow(string s, string t) {
        int slength=s.size();
    	int tlength=t.size();	
    	int alphArray[128];
    	fill_n(alphArray,128,-slength);
    	int minS,minL=INT_MAX;
    	for(int i=0;i<tlength;++i)
    		alphArray[t[i]]=alphArray[t[i]]>0?(++alphArray[t[i]]):1;
    	
    	int start=0;
    	for(int i=0,count=tlength;i<slength;++i)
    	{
    		if((--alphArray[s[i]]>=0) && (--count==0))
    		{
    			while(alphArray[s[start]]<=-slength || (++alphArray[s[start]]<=0))
    				++start;
    			if(minL>i-start+1)
    			{
    				minL=i-start+1;
    				minS=start;
    			}
    			count=1;//因为丢弃了一个
    			++start;
    		}
    	}
    	return minL==INT_MAX?"":s.substr(minS,minL);
    }
};

以上程序中包括了两个头文件：<limits.h>、<algorithm>;前者定义了部分数据类型的极限取值（INT_MAX），后者是STL中相关算法（fill_n）

limits.h头文件内容如下：

C语言的数据类型有四种：整形、浮点型、指针、聚合类型（数组、结构等），其中整形家族的变量包括：char, int, short, long, enum等。浮点数家族包括float, double等。

limits.h头文件对整形家族变量范围进行了宏定义。float.h定义了FLT_MAX, FLT_MIN, DBL_MAX, DBL_MIN。下面这张表搬运自维基百科。

Name	Description	Typical value	ANSI standard minimum- or maximum magnitude value
CHAR_BIT	Number of bits in a char	8	≥+8
SCHAR_MIN	Minimum value for a signed char	–128	≤–127
SCHAR_MAX	Maximum value for a signed char	+127	≥+127
UCHAR_MAX	Maximum value for an unsigned char	+255	≥+255
CHAR_MIN	Minimum value for a char	–128	≤–127 (if char is represented as a signed char ; otherwise ≤0)
CHAR_MAX	Maximum value for a char	+127	≥+127 (if char is represented as a signed char ; otherwise ≥+255)
MB_LEN_MAX	Maximum multi byte length of a character across all locales	varies, usually at least 4	≥+1
SHRT_MIN	Minimum value for a short int	–32,768	≤–32,767
SHRT_MAX	Maximum value for a short int	+32,767	≥+32,767
USHRT_MAX	Maximum value for an unsigned short int	+65,535	≥+65,535
INT_MIN	Minimum value for an int	–2,147,483,648	≤–32,767
INT_MAX	Maximum value for an int	+2,147,483,647	≥+32,767
UINT_MAX	Maximum value for an unsigned int	+4,294,967,295	≥+65,535
LONG_MIN	Minimum value for a long int	32 bit compiler	–2,147,483,648	≤–2,147,483,647
64 bit compiler	–9,223,372,036,854,775,808
LONG_MAX	Maximum value for a long int	32 bit compiler	+2,147,483,647	≥+2,147,483,647
64 bit compiler	+9,223,372,036,854,775,807
ULONG_MAX	Maximum value for an unsigned long int	32 bit compiler	+4,294,967,295	≥+4,294,967,295
64 bit compiler	+18,446,744,073,709,551,615
LLONG_MIN	Minimum value for a long long int	–9,223,372,036,854,775,808	≤-9,223,372,036,854,775,807
LLONG_MAX	Maximum value for a long long int	+9,223,372,036,854,775,807	≥+9,223,372,036,854,775,807
ULLONG_MAX	Maximum value for an unsigned long long int	+18,446,744,073,709,551,615	≥+18,446,744,073,709,551,615