JavaScript Snippet

Two-Pointer Template

Difficulty: Easy

The two-pointer technique is the linear-time answer to many sorted-array problems: pair sums, palindrome checks, in-place reversal, partition. This snippet covers the opposite-ends sweep for sorted-pair targets, the reverse-in-place pattern, and the slow-fast pointer used for in-place mutation. Each fits in 10 lines and runs in O(n) time, O(1) extra space.