Two Sum - Leetcode 1 - HashMap - Javascript
🔔 Two Sum (LeetCode #1) – Optimized Solution | HashMap Approach
📌 LeetCode: https://leetcode.com/problems/two-sum/
In this video, we solve one of the most popular coding interview problems — Two Sum — using the optimized HashMap solution! 💡
This approach drastically improves performance compared to brute force and is ideal for interview prep.
🧠 Problem Overview
You’re given an integer array nums and a target value.
Find indices of the two numbers such that they add up to the target.
⚠️ You can assume exactly one solution exists.
Example:
Input: nums = [2, 7, 11, 15], target = 9
Output: [0, 1]
🚀 Optimized Approach — HashMap (One Pass)
✔️ Use a dictionary (HashMap) to store numbers and their indices
✔️ For each number, check if the complement (target - num) is already in the map
✔️ If yes → return indices
✔️ Else → save number & index in map
📈 Time Complexity: O(n)
📦 Space Complexity: O(n)
🔍 What You’ll Learn in This Video
✨ How to use a HashMap for faster lookups
✨ Why this approach is better than brute force
✨ Example walkthrough with an array
✨ Perfect for interview and competitive coding
💬 Comment Below
Want this solution in another language (Java / C++ / JavaScript)? Let me know! 👇
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