https://leetcode.com/problems/longest-common-prefix/

longest_sub_no_repeats.py

class Solution:
    def lengthOfLongestSubstring(self, s):
        """
        :type s: str
        :rtype: int
        """
        if len(s) < 2: return len(s)
        subs = []
        for x in range(0, len(s)):
            sub = set()
            for y in range(x, len(s)):
                c = s[y]
                if c in sub:
                    break
                else:
                    sub.add(c)
            subs.append(''.join(sub))
        return max(len(sub) for sub in subs)