Longest Substring Without Repeating Characters

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

Example 1:

Input: s = “abcabcbb”
Output: 3
Explanation: The answer is “abc”, with the length of 3. Note that "bca" and "cab" are also correct answers.

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.

Constraints:

• 0 <= s.length <= 5 * 104
• s consists of English letters, digits, symbols and spaces.

My Answer

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        substring = dict() # char, last_appearance_index
        length = 0
 
        max_length = 0
        best_solution_set = None
 
        index = 0
        while index < len(s):
            if s[index] not in substring:
                substring[s[index]] = index
                length += 1
            else:
                if length > max_length:
                    best_solution_set = substring
                    max_length = length
                
                index = substring[s[index]]+1 # change to index last repeated character
                if index >= len(s):
                    break
                substring = {s[index]:index}
                length = 1
            
            if length > max_length:
                    best_solution_set = substring
                    max_length = length
 
            index = index + 1
 
        print(best_solution_set)
        return max_length

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