Lex

Initial Thoughts and Naive Approach

My initial approach was to use brute force—checking every possible substring, seeing if it had any repeating characters, and tracking the longest one. While this method works, it’s not efficient, especially for longer strings. The time complexity of this brute force method is O(n^3), which means it checks every substring of every character, making it impractical for large inputs.

Optimal Approach: Sliding Window Technique

After realizing that brute force wasn't the answer, I started exploring other approaches. That's when I learned about the sliding window technique. The sliding window is a common strategy for problems involving substrings or subarrays, where you maintain a dynamic range (or window) over the input, adjusting it as needed.

What I have learned here is that the first idea which comes to mind is often wrong! It’s important to step back, rethink your approach, and aim for optimization.