Length of longest substring python

length_of_longest_substring.py

class Solution:
    def lengthOfLongestSubstring(self, s: str) -> int:
        cursor = 0
        start = 0
        end = len(s)
        longest = 0
        
        subStringMap = {}
        
        while start < end:
            character = s[start]
            
            if character in subStringMap and subStringMap[character] >= cursor:
                cursor = subStringMap[character] + 1;
                subStringMap[character] = start
            else:
                longest = max(longest, (start + 1) - cursor)
                subStringMap[character] = start
            start = start + 1

        return longest