299. Bulls and Cows

最新推荐文章于 2021-10-08 07:25:11 发布

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本文介绍了一个用于Bulls和Cows猜数字游戏的提示生成算法。该算法通过比较秘密数字与猜测数字来计算正确的数字及其位置（bulls），以及正确数字但错误位置的数量（cows）。实现中考虑了重复数字的情况，并提供了一个C++示例代码。

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".

有题意可知，bull为两个字符串中值和位置都相同的字符个数，cow为两个字符串中值相同但位置不同的字符个数。

class Solution {
public:
    string getHint(string secret, string guess) {
        int Hash[10] = {0}, a = 0, b = 0; 
    for(int i=0; i < secret.size(); i++)
    {
        if(secret[i] == guess[i])
            a++;
        else
        {
            if(Hash[secret[i] - '0']++ < 0) b++;
            if(Hash[guess[i] - '0']-- > 0) b++; 
        }
    }
    return to_string(a) + "A" + to_string(b) + "B";
    }
};