Leetcode question brushing record

Link up https://leetcode.cn/problems/longest-substring-without-repeating-characters/

Slide window template . 

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        cur, res = [], 0
        for r in range(len(s)):
            while s[r] in cur: 
                cur.pop(0) #  On the left 
            cur.append(s[r]) #  The right side will enter the new one anyway 
            res = max(len(cur),res)
        return res