Longest Substring Without Repeating Characters - Leetcode 3 - Python

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

class Solution:

    def lengthOfLongestSubstring(self, s: str) -> int:

        charSet = set()

        left = 0

        ans = 0

        for right in range(len(s)):

            while s[right] in charSet:

                charSet.remove(s[left])

                left+=1

            charSet.add(s[right])

            ans = max(ans, right-left+1)

        return ans

                

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