LeetCode: First Bad Version Solution

Approach

"all the versions after a bad version are also bad"

Example 1

11 2 3 4 5
2G G G B B
3L   M   H
4
51 2 3 4 5
6G G G B B
7      L H

Example 2

11 2 3 4 5
2G B B B B
3L   M   H
4
51 2 3 4 5
6G B B B B
7L M H
8
91 2 3 4 5
10G B B B B
11  L H

Implementation

1var solution = function (isBadVersion) {
2  return function (n) {
3    let lo = 1
4    let hi = n
5
6    while (lo < hi) {
7      let mid = Math.floor((lo + hi) / 2)
8      if (isBadVersion(mid) === false) {
9        lo = mid + 1
10      } else {
11        hi = mid
12      }
13    }
14
15    return lo
16  }
17}

References

Original problem