leet_code[无重复字符的最长子串]

解题思路
题目位置
3.无重复字符的最长子串

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        start=max_len=0
        repeat={}
        for i in range(len(s)):
            if s[i] in repeat and start <= repeat[s[i]]:
                start=repeat[s[i]]+1
            else:
                max_len=max(max_len,i-start+1)
            repeat[s[i]]=i
        return max_len

模范作业

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        
        max_str = ''
        max_len  = 0
        for str in s:
            if str not in max_str:
                max_str += str
                str_len = len(max_str)
                max_len = max_len if max_len > str_len else str_len
            else:
                max_str = max_str[max_str.index(str)+1:]+str 
        return max_len

我认为这样也是可以的，因为本地pycharm编译可以过，但是在leetcode输出为4，不知道为什么

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        max_str = ''
        max_len  = 0
        for str in s:
            if str not in max_str:
                max_str += str
                str_len = len(max_str)
                max_len = max_len if max_len > str_len else str_len
        return max_len