描述
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 returns whether version is bad. Implement a function to find the first bad version. You should minimize the number of calls to the API.
测试用例
Input: n = 5, bad = 4
Output: 4
Explanation:
call isBadVersion(3) -> false
call isBadVersion(5) -> true
call isBadVersion(4) -> true
Then 4 is the first bad version.题解
二分法。
var solution = function(isBadVersion) {
/**
* @param {integer} n Total versions
* @return {integer} The first bad version
*/
return function(n) {
// 二分法
let left = 1, right = n;
while (left < right) {
let mid = Math.floor((left + right) / 2);
if(isBadVersion(mid)) right = mid;
else left = mid + 1;
}
return left;
};
};结果
Accepted
22/22 cases passed (105 ms)
Your runtime beats 28.07 % of javascript submissions
Your memory usage beats 64.6 % of javascript submissions (38.5 MB)
