[leetcode] 374. Guess Number Higher or Lower 解题报告

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这篇博客详细介绍了LeetCode上的374题——Guess Number Higher or Lower的解题过程。作者通过提供题目链接，解释了游戏规则，并指出解题关键在于使用二分搜索算法。在实现代码时，作者注意到了防止溢出的问题。

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题目链接:https://leetcode.com/problems/guess-number-higher-or-lower/

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.

思路: 只是二分就行, 需要注意溢出问题.

代码如下:

// Forward declaration of guess API.
// @param num, your guess
// @return -1 if my number is lower, 1 if my number is higher, otherwise return 0
int guess(int num);

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