用string[i]可以知道此數字的第i+1位數
參考解答:

#include <bits/stdc++.h>
using namespace std;

int main() {
    string num, guess;
    int n, A, B;
    cin >> num >> n;
    while(n--){
        A = B = 0;
        cin >> guess;
        for(int i = 0; i < 4; i++){
            if(guess[i] == num[i]){
                A++;
            }
            for(int j = 0; j < 4; j++){
                if(guess[j] == num[i] && j != i){
                    B++;
                }
            }
        }
        cout << A << 'A' << B << 'B' << endl;
    }
    return 0;
}