def length_of_longest_substring(s: str) -> int: char_set = set() left = 0 max_length = 0 for right in range(len(s)): while s[right] in char_set: char_set.remove(s[left]) left += 1 char_set.add(s[right]) max_length = max(max_length, right - left + 1) return max_length # Example Test Cases print(length_of_longest_substring("abcabcbb")) # Output: 3 print(length_of_longest_substring("bbbbb")) # Output: 1 print(length_of_longest_substring("pwwkew")) # Output: 3 print(length_of_longest_substring("")) # Output: 0 print(length_of_longest_substring("dvdf")) # Output: 3