First Bad Version-LeetCode#278

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.
Example:

Given n = 5, and version = 4 is the first bad version.
call isBadVersion(3) -> false
call isBadVersion(5) -> true
call isBadVersion(4) -> true
Then 4 is the first bad version. 
 思路:二分查找法。
代码如下:
public int firstBadVersion(int n) {
    int start = 1;
    int end = n;
    while (start < end){
        int mid = start + (end - start) / 2;
        if (!isBadVersion(mid)) start = mid + 1;
        else end = mid;
    }
    return start;
}
文章已创建 112

发表评论

您的电子邮箱地址不会被公开。 必填项已用*标注

相关文章

开始在上面输入您的搜索词,然后按回车进行搜索。按ESC取消。

返回顶部