Hot100: Trapping Rain Water (Two Pointers O(n) ACERS Guide)
Subtitle / Summary Trapping Rain Water is the classic boundary-constraint problem. This ACERS guide explains the two-pointer method, key formulas, and runnable multi-language solutions. Reading time: 12–15 min Tags: Hot100, two pointers, array SEO keywords: Trapping Rain Water, two pointers, left right max, O(n), Hot100 Meta description: Two-pointer O(n) trapped water solution with engineering scenarios and multi-language code. A — Algorithm Problem Restatement Given an array of non-negative integers representing bar heights (each width 1), compute how much water can be trapped after raining. ...