python leetcode 3. Longest Substring Without Repeating Characters

子串无重复，遍历字符串。设立一个judge子串来判断：

1. 如果judge中含有当前字符，更新最大值，更新juge
2. 否则judge加上当前字符

class Solution:
    def lengthOfLongestSubstring(self, s):
        """
        :type s: str
        :rtype: int
        """
        l1=len(s)
        if l1<2:
            return l1
        judge=''
        maxlen=0
        for i in range(l1):
            if s[i] in judge:
                maxlen=max(maxlen,len(judge))
                index=judge.find(s[i])
                judge=judge[index+1:]+s[i]
            else:
                judge+=s[i]
        return max(maxlen,len(judge))