class Solution {
public:
    string minWindow(string s, string t) {

        int count=0;
        map<char,int> mp;
        for(char c:t){
            mp[c]++;
        }

        count=mp.size();
        int minWindow=INT_MAX,start=-1,end=-1;
        for(int i=0,j=0;i<s.length();){

            if(count>0){
                if(mp.find(s[j]) != mp.end()){
                    mp[s[j]]--;
                }
                if(mp[s[j]]==0 )    count--;
                j++;
            }else{
                if(mp.find(s[i]) != mp.end()){

                    if(minWindow>j-i){
                        minWindow=j-i;
                        start=i,end=j-1;
                    }
                    if(mp[s[i]]<0)  //there are more of this character
                        mp[s[i]]++;
                    if(mp[s[i]]>0)  count++;
                    i++;
                }
            }
        }

        string res;
        while(start<=end){
            res+=s[start++];
        }
        return res;
    }

};