Longest Substring Without Repeating Characters (LC 3)

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

Example 1:

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

Naive Solution

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        
        maxLength = 0
 
        for i in range(len(s)):
            strSet = set()
            currentLength = 0
 
            for j in range(i, len(s)):
                if s[j] in strSet:
                    break  
                    
                strSet.add(s[j])
                currentLength += 1
 
            maxLength = max(maxLength, currentLength)
 
        return maxLength

Sliding Window Solution

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        
        maxLength = 0
        charSet = set()
        l = 0
        
        for r in range(len(s)):
            
            while s[r] in charSet:
                charSet.remove(s[l])
                l += 1
                
            charSet.add(s[r])
            maxLength = max(maxLength, len(charSet))
        
        return maxLength