class Solution {
private:
    int min(int a, int b)
    {
        if (a < b) return a;
        return b;
    }
public:
    string getHint(string secret, string guess) {
        int a[10] = {}, b[10] = {}, co = 0, bu = 0;
        for (int i = 0; i < secret.size(); ++i)
        {
            a[secret[i] - '0']++;
            b[guess[i] - '0']++;
            if (secret[i] == guess[i]) bu++;
        }
        for (int i = 0; i < 10; ++i) co += min(a[i], b[i]);
        co -= bu;
        return to_string(bu) + 'A' + to_string(co) + 'B';
    }
};