3. Longest Substring Without Repeating Characters - LeetCode

class Solution1:
    def lengthOfLongestSubstring(self, s: str) -> int:
        result, chars = 0, set()
        for j, c in enumerate(s):
            while c in chars:
                i = j - len(chars)
                chars.remove(s[i])
            chars.add(c)
            result = max(result, len(chars))
        return result


class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        result, i, chars = 0, 0, {}
        for j, char in enumerate(s):
            i = max(i, chars.get(char, -1) + 1)
            chars[char] = j
            result = max(result, j - i + 1)
        return result