(java)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.

思路:如果i为bad version 则i后面的都是bad version，如果i不是bad version 则i前面的都不是bad version，用二分查找找到一个i，它前面的都不是bad version，它后面的都是bad version就行了

代码如下(已通过leetcode)

public class Solution extends VersionControl {
    public int firstBadVersion(int n) {
        int low = 1;
        int high = n;
        int ver = 0;
        while (low < high) {
            ver = low + (high - low) / 2;
            if (isBadVersion(ver)) {
                high = ver;
            } else {
                low = ver + 1;
            }
        }
        return low;
    }
}