无重复字符的最长子串

无重复字符的最长子串 - LeetCode (中国) https://leetcode-cn.com/problems/longest-substring-without-repeating-characters/description/

class Solution:
    def lengthOfLongestSubstring(self, s):
        """
        :type s: str
        :rtype: int
        """
        len_ = len(s)
        if len_ == 0:
            return 0
        r, memory_ = 1, ''
        for i in range(len_):
            item_ = s[i]
            if item_ in memory_:
                memory_ = memory_[memory_.find(item_) + 1:]
            memory_ = '{}{}'.format(memory_, item_)
            r = max(len(memory_), r)

        return r