LeetCode：Guess Number Higher or Lower

最新推荐文章于 2025-12-06 07:43:37 发布

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本文介绍了一种使用二分查找法解决猜数字游戏问题的方法。玩家需猜中1到n之间的数字，每次猜测会得到反馈以调整下一次猜测。文章详细解释了二分查找法的应用，并提供了具体的代码实现。

一、问题描述

We are playing the Guess Game. The game is as follows:

I pick a number from 1 to n. You have to guess which number I picked.

Every time you guess wrong, I'll tell you whether the number is higher or lower.

You call a pre-defined API guess(int num) which returns 3 possible results (-1, 1, or 0):

-1 : My number is lower
 1 : My number is higher
 0 : Congrats! You got it!

Example:

n = 10, I pick 6.

Return 6.

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二、解决思路

利用二分查找法，注意每次的mid的取值都是left+(right - left)/2,这点至关重要，开始我没注意到这点，结果就超时没通过~

三、代码

class Solution {
public:
    int guessNumber(int n) {
        if(guess(n) == 0) 
            return n;
        int left = 1,right = n;
        while(left < right){
            int mid = left + (right - left) / 2;
            if(guess(mid) == 0) 
                return mid;
            else if(guess(mid) == 1)
                    left = mid;
                 else
                    right = mid;
        }
        return left;
    }
};