Leetcode 278. First Bad Version

You are a product manager and currently leading a team to develop a new product. Unfortunately, the latest version of your product fails the quality check. Since each version is developed based on the previous version, all the versions after a bad version are also bad.

Suppose you have n versions [1, 2, …, n] and you want to find out the first bad one, which causes all the following ones to be bad.

You are given an API bool isBadVersion(version) which will return whether version is bad. Implement a function to find the first bad version. You should minimize the number of calls to the API.

题目很简单，按数学的说法就是夹逼法。

// Forward declaration of isBadVersion API.bool isBadVersion(int version);class Solution {public:    int firstBadVersion(int n) {        int low=1,high=n,middle;        while(low<high){            middle=low+(high-low)/2;  //没使用 middle=(low+high)/2 , 数学本质上两者相等，但 low+high 可能存在大数溢出的问题            if(!isBadVersion(middle))                low=middle+1;            else                high=middle;        }        return low;    }};