LeetCode 3: Longest Substring Without Repeating Characters | C# Solution | Sliding Window

📝 Solve the classic #slidingwindow problem of finding the longest substring without repeating characters. #strings #hashtable #csharp ⏱️ **Time Complexity**: O(n) where n is the length of the string 🗃️ **Space Complexity**: O(min(m, n)) where m is the size of the character set ## ⏰ Timestamps 00:00 - Understanding problem statement 00:44 - Using Brute Force 02:20 - Brute Force - Big O Notation 03:39 - Using Sliding Window 06:27 - Sliding Window - Big O Notation 07:00 - C# Solution walk-through 08:02 - Solution analysis - runtime + memory ## 🔑 Key Concepts - Sliding Window Technique - Hash Table / Dictionary - String manipulation - Two-pointer approach ## 💡 Learning Points - How to efficiently track character positions using a dictionary - Implementing an optimized sliding window approach - Handling edge cases in substring problems - Using C# collections for efficient lookups ## 🔗 Related Problems - LeetCode 76: Minimum Window Substring - LeetCode 159: Longest Substring with At Most Two Distinct Characters - LeetCode 340: Longest Substring with At Most K Distinct Characters - LeetCode 438: Find All Anagrams in a String ## 👥 Target Audience This video is for software engineers preparing for technical interviews, C# developers looking to improve their algorithm skills, and computer science students learning string manipulation techniques. ## 📚 Prerequisites - Basic understanding of C# syntax - Familiarity with dictionaries/hash tables - Understanding of string operations ## 🔗 Links - [LeetCode Problem](https://leetcode.com/problems/longest-substring-without-repeating-characters/) - [Solution Code](https://shortenertool-qojxs-fa.azurewebsites.net/lc3) ## 💭 Additional Tips - Pay special attention to the optimization that allows us to skip characters rather than checking each one - Notice how we track the current window start position for efficient sliding - Consider the tradeoff between time and space complexity in this solution ## 🎯 Call to Action If you found this solution helpful, please like and subscribe for more C# LeetCode solutions! Share your approaches or questions in the comments below. #codinginterview #leetcode #csharp #algorithmpractice