In this video, I explain how to solve the Contains Duplicate problem using an optimal HashSet approach in C++.
This is a beginner-friendly explanation with a clear approach and step-by-step breakdown — perfect for coding interviews and DSA preparation.
📌 What you’ll learn:
• Problem understanding with examples
• Efficient approach using HashSet
• Step-by-step explanation
• Time and Space Complexity
💡 Problem Statement:
Given an integer array nums, return true if any value appears at least twice, and return false if all elements are distinct.
⏱️ Timestamps:
00:00 Introduction
00:30 Problem Explanation
01:30 Approach (HashSet)
02:30 Code Walkthrough
04:00 Complexity Analysis
🧠 Key Concept:
Using a HashSet helps detect duplicates efficiently in O(n) time.
🎯 Why this problem is important:
• Frequently asked in coding interviews
• Builds strong understanding of hashing
• Foundation for advanced DSA problems
🔔 Don’t forget to:
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