leetcode No.278 第一个错误版本

/* The isBadVersion API is defined in the parent class VersionControl.
      boolean isBadVersion(int version); */
//边界条件不好处理
public class Solution extends VersionControl {
    public int firstBadVersion(int n) {
        int left=1,right=n;
        while(left<=right){
           int mid=left+(right-left)/2;
            if(isBadVersion(mid))
                right=mid-1;
            else
                left=mid+1;
        }
        return left;
    }
}