299. Bulls and Cows 自己写已ac

class Solution {
public:
    string getHint(string secret, string guess) {
        map<char,int> mp;
        if(secret.size()==0)return "";
        int a=0,b=0;
        string ss;
        for(int i=0;i<secret.size();i++){
            if(secret[i]==guess[i]){
                a++;
            }
            else {
                mp[secret[i]]++;
                ss+=guess[i];
            }
        }
        for(int i=0;i<ss.size();i++){
            if(mp[ss[i]]>0){
                b++;
                mp[ss[i]]--;
            }
        }
        return to_string(a)+"A"+to_string(b)+"B";
    }
};