003. longest substring without repeating characters

class :
    def lengthOfLongestSubstring(self, s):
        """
        :type s: str
        :rtype: int
        """
        list_s = list(s)
        for i in range(len(set(list_s)),-1,-1):
            for j in range(0,len(s)-i+1):
                if len(set(list(s[j:j+i]))) == i:
                    return i

class :
    def lengthOfLongestSubstring(self, s):
        """
        :type s: str
        :rtype: int
        """
        finded = {}
        start = 0
        max_length = 0
        for i in range(len(s)):
            if s[i] in finded and finded[s[i]] >= start:
                start = finded[s[i]]+1  
            else:
                if i - start + 1 > max_length:
                    max_length = i - start + 1
            finded[s[i]] = i
        return max_length