76. 最小覆盖子串

跟着别人的代码履了一遍，明天自己再重写遍。

class Solution {
public:
    map<char, int> tstr, sstr;

    bool isContained(){
        for(auto tchar : tstr){
            if(tchar.second > sstr[tchar.first]) return false;
        }
        return true;
    }

    string minWindow(string s, string t) {
        int n1 = s.size(), n2 = t.size();
        if(n1 < n2) return string("");
        int minLength = INT_MAX;
        int ansL = -1;
        for(char tchar : t){
            ++tstr[tchar];
        }
        int left = 0, right = 0;
        for(; right < n1; ++right){
            ++sstr[s[right]];
            if(tstr.find(s[right]) != tstr.end()){
                while(isContained() && left <= right){
                    if(minLength > right - left + 1){
                        ansL = left;
                        minLength = right - left + 1;
                    }
                    --sstr[s[left++]];
                }
            }
        }
        if(ansL == -1) return string("");
        return s.substr(ansL, minLength);
    }
};