LeetCode278. First Bad Version

最新推荐文章于 2025-02-03 15:37:10 发布

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本文介绍了一种使用二分查找算法高效确定首次出现故障的产品版本的方法。通过调用一个布尔型API isBadVersion(version)，该算法可以最小化API调用次数，快速定位到首个故障版本。

问题

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.

答案

很简单，二分查找。但是坑在于 mid = (left + right) / 2; 时可能溢出。
这里写图片描述

public int firstBadVersion(int n) {
    int left = 1, right = n;
    while (left < right) {
        int mid = left + (right - left) / 2;
        if (isBadVersion(mid)) right = mid;
        else left = mid + 1;
    }
    return right;
}