Longest Substring Without Repeating Charactersmedium

def length_of_longest_substring(s: str) -> int:
    # TODO: sliding window with a set or dict
    return 0

print(length_of_longest_substring("abcabcbb"))  # 3
print(length_of_longest_substring("bbbbb"))     # 1
print(length_of_longest_substring("pwwkew"))    # 3