README.md

Longest Substring Without Repeating Characters

This challenge here is to find the longest substring without repeating characters.

You can find the original problem described on LeetCode.

Problem Statement

Given a string s, find the length of the longest substring without repeating characters.

The problem definition on LeetCode also defines what is a substring: "A substring is a contiguous non-empty sequence of characters within a string".

Example 1
Input: s = "abcabcbb"
Output: 3
Explanation: The answer is "abc", with the length of 3.

Example 2
Input: s = "bbbbb"
Output: 1
Explanation: The answer is "b", with the length of 1.

Example 3
Input: s = "pwwkew"
Output: 3
Explanation: The answer is "wke", with the length of 3.
Notice that the answer must be a substring, "pwke" is a subsequence and not a substring.

Constraints

• 0 <= s.length <= 5 * 104
• s consists of English letters, digits, symbols and spaces.

Solutions

I could think of three possible approaches one could use to solve this issue.
You can find a complete walkthrough of my solutions on my post.
Below is a table with a summary of the solutions.

Solutions	Time	Space
Brute Force	O(n²)	O(min(m,n))
Sliding Window	O(n)	O(min(m,n))
Optimized Sliding Window	O(n)	O(1)