Pattern

Binary Search

Divide and conquer with logarithmic time complexity.

7 Problems

0 Easy

7 Medium

0 Hard

How Binary Search Works

Binary Search eliminates half the search space with each comparison. Starting with a range [low, high], you check the middle element and decide whether the answer lies in the left or right half. This gives O(log n) time complexity. Beyond basic sorted array search, binary search applies to any problem where you can define a monotonic condition — a boundary where values go from "no" to "yes" (or vice versa). You're essentially searching for that boundary.

When to Use Binary Search

Pattern Recognition

Look for these trigger words in problem statements:

binary search binary-search search a 2d matrix koko eating bananas search in rotated sorted array find minimum in rotated sorted array time based key-value store median of two sorted arrays

Common Mistakes

Infinite loops from incorrect mid calculation or boundary updates (use low + (high - low) // 2)
Off-by-one errors in the loop condition: while low <= high vs while low < high
Not correctly identifying the search space — sometimes you search on the answer, not the array
Forgetting that binary search requires a monotonic property to work correctly

When NOT to Use Binary Search

When the array is unsorted and you can't sort it
When there's no monotonic property to exploit
When the search space is tiny (linear scan is simpler and equally fast)

Practice Problems

Easy (0) Medium (7) Hard (0)

Binary Search medium Search a 2D Matrix medium Koko Eating Bananas medium Search in Rotated Sorted Array medium Find Minimum in Rotated Sorted Array medium Time Based Key-Value Store medium Median of Two Sorted Arrays medium

Master Binary Search

Build pattern recognition with interactive MCQs. Understand why to use Binary Search, not just how.

Download LeetEye Free