Solution: First Bad Version

Explore how to apply a modified binary search to identify the first bad software version in a sorted sequence, minimizing calls to the version-check API. This lesson guides you through the step-by-step implementation, highlights the time and space complexity advantages, and helps you master this common interview problem pattern.

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Statement
Solution
- Naive approach
- Optimized approach using modified binary search

Statement

You are managing a product development team, and the latest release has failed quality checks. Because each version is built on top of the previous one, once a version is bad, every version after it is also bad.

You are given an array of n versions $[1, 2, …, n]$ , and your task is to determine the first version in this sequence that is bad—the version that causes all later versions to be bad as well.

You have access to an API IsBadVersion(version) that returns TRUE if a given version is bad.

Your task is to find the first bad version while minimizing the number of calls to this API.

Constraints:

$1 \leq$ bad ...