【Leetcode299】Bulls and Cows

有个小细节，同样位置同样的数，不算作cow。计数排序的思想，因为对于cows，不管出现在哪儿，我只想知道每个数字在两个字符串中出现的最少次数。 

class Solution {
public:
    string getHint(string secret, string guess) {
        vector<int> secret_count(10, 0);
        vector<int> guess_count(10, 0);
        size_t same_number = 0;
        for(size_t index = 0; index < secret.size(); ++index){
            if(secret[index] == guess[index])
                same_number++;
            else{
                secret_count[secret[index]-'0']++;
                guess_count[guess[index]-'0']++;
            }
        }
        size_t number = 0;
        for(size_t i = 0; i < 10; ++i){
            number += std::min(secret_count[i], guess_count[i]);
        }
        string answer = to_string(same_number) + "A" + to_string(number) + "B";
        return answer;
    }
};