1 /**
2 * class VersionControl {
3 * public:
4 * static bool isBadVersion(int k);
5 * }
6 * you can use VersionControl::isBadVersion(k) to judge whether
7 * the kth code version is bad or not.
8 */
9 class Solution {
10 public:
11 /**
12 * @param n: An integers.
13 * @return: An integer which is the first bad version.
14 */
15 int findFirstBadVersion(int n) {
16 // write your code here
17 int l = 1, r = n;
18 while (l < r) {
19 int m = (l + r) / 2;
20 if (VersionControl::isBadVersion(m)) r = m;
21 else l = m + 1;
22 }
23 return l;
24 }
25 };
