Solution for LeetCode Bulls and Cows

BullsAndCows.java

public class BullsAndCows {
    public String getHint(String secret, String guess) {
        int n = secret.length();
        int[] map = new int[10];
        int a = 0;
        int b = 0;
        for (int i = 0; i < n; i++) {
            int s = secret.charAt(i) - '0';
            int g = guess.charAt(i) - '0';
            if (s == g) {
                a++;
            } else {
                if (map[s] < 0) {
                    b++;
                }
                if (map[g] > 0) {
                    b++;
                }
                map[s]++;
                map[g]--;
            }
        }
        return a + "A" + b + "B";
    }
}