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Trapping Rain Water with two pointers — why does leftMax/rightMax work in O(1) space?

Q: Trapping Rain Water with two pointers — why does leftMax/rightMax work in O(1) space?

**Core concept.** Trapping Rain Water with two pointers is a classic interview signal. Input n steps Optimal O(n log n) Result Verified How it works — use optimal structure, maintain invariants, handle empty/single/duplicate. Brute O(n²) vs optimal O(n) or O(n log n). | | Brute | Optimal | |---|---|---| | Time | O(n²) | O(

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Core concept. Trapping Rain Water with two pointers is a classic interview signal.

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