First Bad Version

0Easy

First Bad Version

You have n versions [1..n]. isBadVersion(version) tells if a version is bad. All versions after the first bad one are also bad. Find the first bad version minimizing API calls using binary search.

Example 1:

n = 5, bad = 4 → isBadVersion(3)=false, isBadVersion(5)=true, isBadVersion(4)=true → Output: 4

Example 2:

n = 1, bad = 1 → Output: 1

Jnaneshwara Reddy Satti

Builder · ClearCode

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Algorithm Visualizer

O(log N)

Before starting this video, please check the description to ensure you know the prerequisites. If you're comfortable with arrays and hash maps, let's go!

TEST CASE: []O(1)

clearcode.in

Execution Trace

1def firstBadVersion(n):

2 left, right = 1, n

3 while left < right:

4 mid = left + (right - left) // 2

5 if isBadVersion(mid):

6 right = mid

7 else:

8 left = mid + 1

9 return left

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First Bad Version — Easy Arrays Algorithm | ClearCode