Random Pick Index & Reservoir Sampling Explained | Coding Interview Problem

Description:
Learn how to solve the Random Pick Index problem efficiently using Reservoir Sampling! ????

In this video, we tackle a common coding interview question where we need to randomly select an index of a target number from an array with duplicates. We explore why a simple HashMap solution might consume too much memory and how Reservoir Sampling offers a space-optimized O(1) alternative.

We break down the probability logic step-by-step to prove that every index has an equal chance of being selected. Whether you are preparing for technical interviews or just want to learn a cool algorithm, this guide is for you! ????

Topics covered:
- Problem understanding and constraints
- Naive HashMap approach
- Introduction to Reservoir Sampling
- Step-by-step walkthrough and mathematical proof
- Python implementation and complexity analysis

Happy Coding! ????✨

Chapters:
00:00 - Introduction
00:13 - Problem Statement
00:31 - Example Scenario
00:51 - Solution Approaches
01:08 - Naive Solution Analysis
01:25 - Reservoir Sampling Intro
01:40 - The Logic
01:56 - Walkthrough
02:16 - Mathematical Proof
02:36 - Code Snippet
02:52 - Complexity Analysis
03:10 - Conclusion
03:29 - Outro

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