3. Longest Substring Without Repeating Characters

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

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.

def lengthOfLongestSubstring(self, s: str) -> int:
	i = 0
	j = 0
	seen = set()
	length = 0

	while j < len(s):
		if s[j] not in seen:
			seen.add(s[j])
			j += 1
			length = max(length, j - i)
		else:
			seen.remove(s[i])
			i += 1

	return length