Longest Substring Without Repeating Characters

1def lengthOfLongestSubstring(s):
2    maxLen = 0
3    left = 0
4    charSet = set()
5
6    for right in range(len(s)):
7        while s[right] in charSet:
8            charSet.remove(s[left])
9            left += 1
10        charSet.add(s[right])
11        maxLen = max(maxLen, right - left + 1)
12
13    return maxLen