Longest Substring Without Repeating Characters | LeetCode 3 | Sliding Window | Java

In this video, we solve LeetCode 3 – Longest Substring Without Repeating Characters using the Sliding Window approach in Java. We’ll understand the problem step by step and learn how to find the length of the longest substring that contains no repeating characters. 🔹 Problem: Longest Substring Without Repeating Characters 🔹 LeetCode: #3 🔹 Language: Java 🔹 Approach: Sliding Window + HashMap 🔹 Difficulty: Medium What you'll learn: ✅ Sliding Window technique ✅ How to use HashMap to store character positions ✅ How to move the left pointer efficiently ✅ How to handle repeating characters ✅ How to maintain the maximum substring length ✅ Writing clean and optimized Java code ✅ Step-by-step dry run and explanation ⏱️ Time Complexity: O(n) 💾 Space Complexity: O(min(n, character set size)) This is one of the most important Sliding Window pattern questions for coding interviews and DSA preparation. 👍 If you find the explanation helpful, like the video and subscribe for more LeetCode and DSA tutorials. #LeetCode #Java #DSA #SlidingWindow #LongestSubstring #LeetCode3 #CodingInterview #Programming #InterviewPreparation