Count Residue Prefixes | Prefix + Hashing Trick | LeetCode Easy Explained | Shecodes_

In this video, we solve the LeetCode problem *Count Residue Prefixes* step by step in a beginner-friendly way.

We focus on:
✔ Understanding the problem from basics
✔ Prefix length % 3 intuition
✔ How to track distinct characters efficiently
✔ Why prefixes with length multiple of 3 never work
✔ Optimized O(n) approach using frequency array
✔ Clean and simple C++ implementation

This video is perfect for:
• Beginners learning Prefix problems
• Students preparing for DSA interviews
• Anyone struggling with distinct character logic
• LeetCode beginners

📌 Key Insight:
A prefix is a residue if:
Number of distinct characters == (prefix length % 3)

🧠 Time Complexity: O(n)
🧠 Space Complexity: O(1)

💻 Language Used: C++

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📌 Examples Covered:
• "abc"
• "dd"
• "bob"
• "aaaa"

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