Trapping Rain Water | DSA Interview Question | Optimal & Intuitive Explanation

In this video, we solve the Trapping Rain Water problem — one of the most important DSA interview questions asked in FAANG & top product-based companies.
You’ll learn the core intuition, brute force approach, prefix & suffix method, and the optimal two-pointer solution with step-by-step explanation.

This problem helps you master:

Array processing

Prefix & Suffix concepts

Two Pointer Technique

Space & Time Optimization

📌 Problem Statement
Given n non-negative integers representing an elevation map, compute how much rainwater can be trapped after raining.

🚀 Approaches Covered
✅ Brute Force Approach (O(n²))
✅ Prefix & Suffix Max Arrays (O(n), extra space)
✅ Two Pointer Optimal Approach (O(n), O(1) space)

⏱️ Time & Space Complexity
Time: O(n)

Space: O(1) (Two Pointer approach)

🎯 Asked In
Google | Amazon | Microsoft | Meta | Flipkart | Adobe

💡 Why You Should Watch This
✔️ Clear visualization
✔️ Beginner-friendly explanation
✔️ Interview-focused logic
✔️ Perfect for DSA revision

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