_299.java

package com.fishercoder.solutions;

/**
 * 299. Bulls and Cows
 *
 * 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.

 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".
 You may assume that the secret number and your friend's guess only contain digits, and their lengths are always equal.*/
public class _299 {
    public static class Solution1 {
        public String getHint(String secret, String guess) {
            int[] secretCows = new int[10];
            int[] guessCows = new int[10];
            int bulls = 0;
            for (int i = 0; i < secret.length(); i++) {
                if (guess.charAt(i) == secret.charAt(i)) {
                    bulls++;
                } else {
                    secretCows[Character.getNumericValue(secret.charAt(i))]++;
                    guessCows[Character.getNumericValue(guess.charAt(i))]++;
                }
            }
            int cows = 0;
            for (int i = 0; i < 11; i++) {
                cows += Math.min(secretCows[i], guessCows[i]);
            }
            return bulls + "A" + cows + "B";
        }
    }
}