Two Pointer Technique: When to Use It and 6 Problems Solved

Sun, 05 Jul 2026 10:00:00 +0500

Every interview prep list mentions the two pointer technique, and almost every explanation makes the same mistake: it shows you solutions without teaching you recognition. You read the Two Sum II solution, nod along, and then freeze in a real interview because nobody told you what a two pointer problem looks like before you know the answer.

Here’s the framing that fixes it: two pointers is a technique for eliminating candidate pairs (or subarrays) without checking them, the same way binary search eliminates candidates without visiting them. The brute-force approach to most pair problems checks all O(n²) pairs. Two pointers gets to O(n) by proving, at each step, that a whole batch of pairs can’t possibly be the answer.

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Two Pointer Technique: When to Use It and 6 Problems Solved