leetcode 278. 第一个错误的版本

java:

二分简单题重拳出击！ 

public class Solution extends VersionControl {
    public int firstBadVersion(int n) {
        int l = 1, r = n;
        while(l < r){
            int m = l + (r - l ) / 2;
            if(isBadVersion(m)){
                r = m;
            }else{
                l = m + 1;
            }
        }
        return l;
    }
}