The code base version is an integer start from 1 to n. One day, someone committed a bad version in the code case, so it caused this version and the following versions are all failed in the unit tests. Find the first bad version.

You can call isBadVersion to help you determine which version is the first bad one. The details interface can be found in the code’s annotation part.

Notice
Please read the annotation in code area to get the correct way to call isBadVersion in different language. For example, Java is SVNRepo.isBadVersion(v)

Example
Given n = 5:

isBadVersion(3) -> false
isBadVersion(5) -> true
isBadVersion(4) -> true
Here we are 100% sure that the 4th version is the first bad version.

Challenge
You should call isBadVersion as few as possible.
OOXX二分法(find the first X)。特征：布尔值哪一种。O：false；X：true。

数组很长 不知道重点 所以先找到一个 区间范围 2k 3k可以接受，也不能太大
logk的时间内

动态数组 x2 double 倍增思想
乘logk 次【k，2k】之间

/**
 * public class SVNRepo {
 *     public static boolean isBadVersion(int k);
 * }
 * you can use SVNRepo.isBadVersion(k) to judge whether 
 * the kth code version is bad or not.
*/

强调审题
首先他是 只要>=范围之内的 都是true  所以min=end；
返回flase说明选的范围小了
不存在之前的考虑等号的问题
其他的一样

public class Solution {
    /*
     * @param n: An integer
     * @return: An integer which is the first bad version.
     */
    public int findFirstBadVersion(int n) {
        // write your code here
        int start = 1;
        int end = n;
        while (start + 1 < end){
            int mid = start + (end - start) / 2;
            if (SVNRepo.isBadVersion(mid)){
                end = mid;
            } else {
                start = mid;
            }
        }
        if (SVNRepo.isBadVersion(start)){
            return start;
        }
        return end;
    }
}