Longest Substring with K Distinct Characters | Sliding Window | LeetCode Solution in Java

In this video, we solve the LeetCode problem "Longest Substring with K Unique Characters" using the efficient Sliding Window + HashMap approach in Java. You'll learn how to track character frequencies and dynamically shrink the window when needed. We'll also walk through edge cases and dry-run the solution with examples like "aabacbebebe" and "aaaa".

🔍 Problem:
Given a string and an integer k, find the length of the longest substring with exactly k distinct characters. If no such substring exists, return -1.

✅ Perfect for beginners and intermediate coders preparing for technical interviews.

🧠 Concepts Covered:

Sliding Window Technique

HashMap for Frequency Count

Dynamic Window Shrinking

Handling Edge Cases

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📅 Problem Date: LeetCode Daily Challenge – July 3, 2025
🧑‍💻 Language: Java

Видео Longest Substring with K Distinct Characters | Sliding Window | LeetCode Solution in Java канала Sagar Dahiwal