48. 最长不含重复字符的子字符串

题目链接：https://leetcode-cn.com/problems/zui-chang-bu-han-zhong-fu-zi-fu-de-zi-zi-fu-chuan-lcof/
难度：中等

描述：
请从字符串中找出一个最长的不包含重复字符的子字符串，计算该最长子字符串的长度。

题解

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        char_set = set()
        left = 0
        ret = 0
        for right in range(len(s)):
            if s[right] in char_set:
                while s[right] in char_set:
                    char_set.remove(s[left])
                    left += 1
            char_set.add(s[right])
            ret = max(ret, right - left + 1)
        return ret