Longest substring without repeating characters

Length of the Longest Substring Without Repeating Characters

Are you interested in solving one of the most common and challenging coding problems? In this video, we’ll guide you step-by-step on how to find the length of the longest substring without repeating characters. This problem is not only a popular interview question but also a great way to strengthen your problem-solving skills in string manipulation and sliding window techniques.

Problem Statement

The challenge is to find the length of the longest substring in a given string that does not contain any repeating characters. For example, if the input string is "abcabcbb", the output should be 3, since the longest substring without repeating characters is "abc".

Key Concepts Covered

To solve this problem efficiently, we’ll be using a sliding window approach combined with a hash set to track characters in the current substring. Here’s a breakdown of the steps:

1. Sliding Window Technique: We maintain a dynamic window of characters that adjusts as we iterate through the string.
2. Hash Set for Uniqueness: The hash set helps in keeping track of unique characters and efficiently checks for duplicates.
3. Optimized Time Complexity: We’ll achieve a time complexity of O(n), making the solution scalable even for large inputs.

Implementing the Solution

We’ll dive into the coding part, where you’ll learn:

• Initializing two pointers for the sliding window.
• Iterating through the string while expanding and shrinking the window based on character uniqueness.
• Keeping track of the maximum length of a valid substring.

Detailed Code Walkthrough

In this section, we’ll explain the logic behind the code and walk you through a clean and optimized implementation. You’ll understand:

• How to manage the sliding window using two pointers (start and end).
• When to add or remove characters from the hash set.
• Updating the maximum length when a new non-repeating substring is found.

Handling Edge Cases

No solution is complete without considering edge cases. We’ll cover:

• What happens when the input string is empty.
• How the solution handles strings with all unique characters.
• Dealing with inputs that have all identical characters.

Applications and Importance

This problem is not just theoretical; it has practical applications in fields like:

• Text Processing: Finding unique sequences or tokens in large texts.
• Data Stream Analysis: Identifying non-repetitive patterns in real-time data streams.
• Interview Preparation: Strengthening your understanding of sliding window techniques, which are crucial for many coding interviews.

Conclusion

By the end of this video, you’ll be equipped with a clear understanding of how to solve the problem of finding the length of the longest substring without repeating characters. You’ll also gain valuable insights into applying sliding window techniques and managing character uniqueness in strings.

For a detailed step-by-step guide, check out the full article: https://origin.geeksforgeeks.org/length-of-the-longest-substring-without-repeating-characters/.