LeetCode 3: Longest Substring Without Repeating Characters | C++ Solution | Step-by-Step Explanation

LeetCode 3: Longest Substring Without Repeating Characters | C++ Solution | Step-by-Step Explanation Welcome to CodeWithBK — your go-to hub for mastering LeetCode + DSA with C++ programming. 🧠 Concepts Covered: strings, unordered_set in C++ In this tutorial, we break down LeetCode Problem 3: Longest Substring Without Repeating Characters, and build a clean, efficient C++ solution using the sliding-window technique. Perfect for interview prep and mastering string algorithms! 🚀 💡 What You’ll Learn: 🔍 Problem Understanding – Define substrings vs. subsequences and sample cases like "pwwkew" where the answer is 3 ("wke") 🧠 Optimal Pattern – Use a sliding window with two pointers and a hash set/map to maintain a substring without duplicates. 📝 C++ Code Walkthrough – Step through the implementation, including pointer movement, window adjustments, and using unordered_set of characters 📊 Complexity Insight – Achieve O(n) time and O(min(n, m)) space (where m is character set size) 🧪 Edge Cases – Handle empty strings and repeated characters efficiently 🧠 Perfect for: C++ programming learners Coding interview preparation Practicing problems on strings 👨‍💻 Timestamps: 00:00 – Introduction 00:47 – problem description 02:22 – algorithm and c++ code solution 16:13 – submitting the code 🧑‍💻 Want more LeetCode problems solved in C++? Check out the full LeetCode C++ Playlist on CodeWithBK! :    • C++ DSA Solutions | LeetCode Problem Solvi...   👍 Don't forget to like, comment, and subscribe for more tutorials on C++ LeetCode solutions and other coding topics! 💬 Got questions? Drop them in the comments—we love helping out! Stay connected: Subscribe:    / @codewithbk   Email: [email protected] Discord:   / discord   Instagram ▶️   / balkrishna_srivastava   Coding mentor profile: https://www.codementor.io/@balkrishna... For 1:1 sessions, reach out to me here : https://www.codementor.io/@balkrishna... My YouTube channel where I teach in Hindi :    / @codewithbkhindi   #LeetCode #CodeWithBK #CppProgramming #CPPTutorial #DSA #LeetCodeSolution #DSAInCPP #InterviewQuestions #StringProblems #CPPProgramming