Leetcode-Longest Substring Without Repeating Characters Python

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        final = []
        maxlength = 0
        index = 0
        i = index
        while(i<len(s)):
            if(s[i] not in final):    #查看是否存在重复
                final.append(s[i])
                i+=1
            else:
                index+=1
                i = index
                final = []
            if(len(final)>maxlength):
                maxlength = len(final)
        return maxlength