Bulls and Cows.java

/*
    You are playing the following Bulls and Cows game with your friend: You write down a number and ask your friend to guess 
    what the number is. Each time your friend makes a guess, you provide a hint that indicates how many digits in said guess 
    match your secret number exactly in both digit and position (called "bulls") and how many digits match the secret number 
    but locate in the wrong position (called "cows"). Your friend will use successive guesses and hints to eventually derive 
    the secret number.

    Link: https://leetcode.com/problems/bulls-and-cows/

    Example: For example:
		Secret number:  "1807"
		Friend's guess: "7810"
		Hint: 1 bull and 3 cows. (The bull is 8, the cows are 0, 1 and 7.)
	Write a function to return a hint according to the secret number and friend's guess, use A to indicate the bulls and 
	B to indicate the cows. In the above example, your function should return "1A3B". Please note that both secret number 
	and friend's guess may contain duplicate digits, for example:
		Secret number:  "1123"
		Friend's guess: "0111"
	In this case, the 1st 1 in friend's guess is a bull, the 2nd or 3rd 1 is a cow, and your function should return "1A1B".

    Solution: None
    
    Source: https://leetcode.com/discuss/82140/4ms-easy-to-understand-java-solution
*/

public class Solution {
    int bull = 0;
    int cow = 0;
    int[] s = new int[10];
    int[] g = new int[10];

    public String getHint(String secret, String guess) {
        for (int i = 0; i < secret.length(); i++) {
            if (secret.charAt(i) == guess.charAt(i)) {
            	bull++;
            }
        }
        for (int i = 0; i < secret.length(); i++) {
            s[secret.charAt(i) - 48]++;
            g[guess.charAt(i) - 48]++;
        }
        for (int i = 0; i < 10; i++) {
            cow += Math.min(s[i],g[i]);
        }
        cow -= bull;
        return bull + "A" + cow + "B";
    }
}