Two Pointers
Coming soonLearn when a pair of indices moving through a sequence collapses a quadratic brute force into a single linear pass.
12
Planned lessons
11
Coding problems
6h
Est. study time
Easy
Difficulty
Overview
The two-pointer pattern uses a pair of indices moving through a sequence to replace a quadratic brute force with a single linear pass. You'll learn converging pointers, fast/slow pointers, and partitioning.
Why it matters
Two pointers is one of the highest-leverage patterns: once you recognise it, an O(n²) solution collapses to O(n) with O(1) extra space — exactly the optimisation interviewers are looking for.
What the course will cover
- Converging pointers on sorted arrays
- Fast and slow pointers for cycle detection
- Partitioning and the Dutch national flag problem
- Pair, triplet, and container problems
- Patterns: Two Sum II, 3Sum, Trapping Rain Water
Interview relevance
Two-pointer problems are a staple of phone screens and often the follow-up optimisation an interviewer expects after your first brute-force attempt.
Topics you'll master
In the meantime, dive into a published track to keep your momentum.