无重复字符的最长子串

def solve():
    def lengthOfLongestSubstring(____):
        char_set = set()
        left = ____
        max_len = ____
        for right in range(len(____)):
            while s[right] in char_set:
                char_set.remove(____)
                left += ____
            char_set.add(____)
            max_len = max(____)
        return max_len
    print(lengthOfLongestSubstring(____))