java
class Solution {
public String getHint(String secret, String guess) {
int bulls = 0;
int[] cntS = new int[10];
int[] cntG = new int[10];
for (int i = 0; i < secret.length(); ++i) {
if (secret.charAt(i) == guess.charAt(i)) {
++bulls;
} else {
++cntS[secret.charAt(i) - '0']; //不太懂
++cntG[guess.charAt(i) - '0']; //不太懂
}
}
int cows = 0;
for (int i = 0; i < 10; ++i) {
cows += Math.min(cntS[i], cntG[i]);
}
return Integer.toString(bulls) + "A" + Integer.toString(cows) + "B";
}
}
