Binary Search — Classic LeetCode 278

First Bad Version / visualized

No array to index — only an API isBadVersion(v). Versions are monotonic: once one version is bad, every later version is bad too. Binary search for the first bad version by treating “good → bad” as the boundary to find.

n (versions 1…n)

First bad (hidden truth)

Execution

idle

Press Run to begin.

0 / 0

Speed

Java · running line

left mid right good (API) bad (API) first bad

O(log n) API calls · O(1) space · when mid is bad keep it (right = mid); when good, left = mid + 1.