I have been trying to implement this logic but got stuck

Question : https://leetcode.com/problems/longest-substring-without-repeating-characters/description/

Given a string s, find the length of the longest substring without repeating characters.

Example 1:

Input: s = "abcabcbb"
Output: 3
Explanation: The answer is "abc", with the length of 3.

Example 2:

Input: s = "bbbbb"
Output: 1
Explanation: The answer is "b", with the length of 1.

Example 3:

Input: s = "pwwkew"
Output: 3
Explanation: The answer is "wke", with the length of 3.
Notice that the answer must be a substring, "pwke" is a subsequence and not a substring.

‘s’ consists of English letters, digits, symbols and spaces.

code:

s = "pwwkew"
s = [ i for i in s]
lst = []
cnt = 0

if len(set(s)) == 1:
    print(1)
else:
    for i in s:
        if i not in lst:
            lst.append(i)
        else:
            if len(lst) == 0:
                lst.remove(i)
                lst.append(i)
            else:
                lst.pop(0)
                lst.append(i)
w = ''.join(map(str,lst))
for i in range(2,len(''.join(map(str,lst)))):
    print(w[:i])

What is that i am missing as logic in my code ?