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DSA Pattern

Two Pointer Pattern

Recognise the Two Pointer pattern once — then solve any problem that uses it. Below are every Two Pointer problem we index, grouped by the module that teaches them.

Problems

Walkthroughs ready

4E · 1M · 0H

Difficulty mix

Java · Python

Languages

Where this pattern shows up

Two Pointer problems by module

Arrays & Hashing4 problems

Funny String

hackerrankAmazon

easyExplained

HackerRank in a String

AmazonMicrosoftGoogle

easyExplained

Palindrome Index

AmazonMicrosoftGoogle

Binary Search1 problem

Pairs

AmazonMicrosoftadobe

mediumExplained

Pattern guide

Mastering the Two Pointer pattern

Overview

The Two Pointer pattern is one of the reusable techniques that experienced candidates spot instantly. Rather than memorising individual problems, strong interviewees recognise that a new question "is just Two Pointer" and reach for the matching template. That recognition is exactly what this collection is designed to build.

We index 5 problems that use the Two Pointer pattern (4 easy, 1 medium, 0 hard), each worked brute-force → optimal in Java and Python with line-by-line explanations. Solving them back-to-back is the fastest way to internalise when and how to apply Two Pointer.

Pattern-first practice compounds: once Two Pointer is automatic, you'll see it inside problems that never mention it by name.

Study playbook

1
Solve them in a single sitting
Work several Two Pointer problems in a row. The shared skeleton becomes obvious when you see the same structure solve different-looking questions.
2
Name the trigger
Write down the signal that should make you reach for Two Pointer (e.g. 'contiguous sub-range', 'sorted + pair', 'k largest'). In the interview, that trigger is your cue.
3
Keep one template
Maintain a single mental template for Two Pointer that you can write from memory and adapt, instead of re-deriving it under pressure.
4
Compare with neighbours
Know how Two Pointer differs from adjacent patterns so you pick the right tool when a problem could go more than one way.

Common pitfalls

Forcing Two Pointer onto a problem that doesn't fit because it's the pattern you just practised.
Recalling a specific solution instead of re-deriving from the pattern when given a variation.
Skipping the brute force and the complexity discussion that frame your optimal answer.
Missing the edge cases the pattern is notorious for (empty input, boundaries, duplicates).

Frequently asked

What is the Two Pointer pattern?

It's a reusable problem-solving technique that recurs across many interview questions. Learning it once lets you solve a whole family of problems instead of memorising each one.

When should I use Two Pointer?

When a problem shows the pattern's trigger signal. The problems below all share that signal, so working through them trains you to recognise it quickly.

How many Two Pointer problems should I do?

Enough that the template feels automatic — usually solving the indexed set here in sequence is sufficient to recognise Two Pointer on sight.

Related patterns

Two Pointers34 Two Heaps1 Two Pointer Pairing1

Keep exploring

Browse DSA another way

Curriculum

18 modules · theory + practice

Explore

Curated sheets

Blind 75, NeetCode 150, Grind 75

DSA Pattern

Two Pointer Pattern

Recognise the Two Pointer pattern once — then solve any problem that uses it. Below are every Two Pointer problem we index, grouped by the module that teaches them.

Problems

Walkthroughs ready

4E · 1M · 0H

Difficulty mix

Java · Python

Languages

Where this pattern shows up

Two Pointer problems by module

Arrays & Hashing4 problems

Funny String

hackerrankAmazon

easyExplained

HackerRank in a String

AmazonMicrosoftGoogle

easyExplained

Palindrome Index

AmazonMicrosoftGoogle

Binary Search1 problem

Pairs

AmazonMicrosoftadobe

mediumExplained

Pattern guide

Mastering the Two Pointer pattern

Overview

Pattern-first practice compounds: once Two Pointer is automatic, you'll see it inside problems that never mention it by name.

Study playbook

1
Solve them in a single sitting
Work several Two Pointer problems in a row. The shared skeleton becomes obvious when you see the same structure solve different-looking questions.
2
Name the trigger
Write down the signal that should make you reach for Two Pointer (e.g. 'contiguous sub-range', 'sorted + pair', 'k largest'). In the interview, that trigger is your cue.
3
Keep one template
Maintain a single mental template for Two Pointer that you can write from memory and adapt, instead of re-deriving it under pressure.
4
Compare with neighbours
Know how Two Pointer differs from adjacent patterns so you pick the right tool when a problem could go more than one way.

Common pitfalls

Forcing Two Pointer onto a problem that doesn't fit because it's the pattern you just practised.
Recalling a specific solution instead of re-deriving from the pattern when given a variation.
Skipping the brute force and the complexity discussion that frame your optimal answer.
Missing the edge cases the pattern is notorious for (empty input, boundaries, duplicates).

Frequently asked

What is the Two Pointer pattern?

It's a reusable problem-solving technique that recurs across many interview questions. Learning it once lets you solve a whole family of problems instead of memorising each one.

When should I use Two Pointer?

When a problem shows the pattern's trigger signal. The problems below all share that signal, so working through them trains you to recognise it quickly.

How many Two Pointer problems should I do?

Enough that the template feels automatic — usually solving the indexed set here in sequence is sufficient to recognise Two Pointer on sight.