Master Coding Interviews : Part 2 ( Two Pointers Pattern )

If you read Part 1 of this series, you already know how a single pattern can transform a slow, brute-force solution into an elegant, optimized one. Today we're going to do the same thing — but with a different tool in our belt: the Two Pointers pattern. This one is everywhere in coding interviews. Once you recognize it, you'll start seeing it in problems you might have struggled with before. What is the Two Pointers Pattern? The idea is simple: instead of using one index to iterate through your data structure, you use two. These two pointers move through the array (or string) according to specific conditions, and together they help you find the answer without needing nested loops. There are two main variants you'll encounter: Opposite-direction pointers : One pointer starts at the beginning, the other at the end. They move toward each other until they meet. Same-direction pointers (fast & slow) : Both pointers start at the same end, but move at different speeds or under different c