Leetcode - Medium

3. Longest Substring Without Repeating Characters [Original Spec] [2024-01-21]

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        starts = {} # [ord(char)]: the first valid index for a string containing the char
        curr_longest = 0
        last_start = 0
        for i, c in enumerate(s):
            if c in starts:
                tmp = i - last_start
                if tmp > curr_longest: curr_longest = tmp
                if starts[c] > last_start: last_start = starts[c]
            starts[c] = i + 1
        return max(curr_longest, len(s) - last_start)