假C/C++ language... :
#include <stdio.h>
#include <stdlib.h>
char ques[] = "1234"
char ans[] = "0123";
int ans_l[10] = {-1};
int a = 0;
int b = 0;
int temp = 0;
for (int i = 0; i < 4; ++i)
ans_l[atoi(ans)] = i; // atoi() convert char to int, and fetch answer's char into array list
// 差点就end了 = =|
for (int i = 0; i < 4; ++i)
if ((temp = ans_l[atoi(ques)]) >= 0) // if the question's char is in the answer
if (temp == i) // A
++a;
else // B
++b;
printf("%dA%dB", a, b);