import sys


class Solution:
    def __init__(self):
        self.number_set: set[int] = set()  # 哈希表，全 O(1)
        self.longest_length: int = 1

    def longestConsecutive(self, nums: list[int]) -> int:
        if not nums: return 0
        self.number_set = set(nums)  # O(n)
        for n in self.number_set:
            # n = self.number_set.pop()
            # print(n, file=sys.stderr)
            current_length: int = 1
            if n + 1 in self.number_set:
                continue
            # pointer = n
            # while True:
            #     if pointer + 1 in self.number_set:
            #         pointer += 1
            #         current_length += 1
            #         self.number_set.remove(pointer)
            #     else:
            #         break
            pointer = n
            while True:
                if pointer - 1 in self.number_set:
                    pointer -= 1
                    current_length += 1
                    # self.number_set.remove(pointer)
                else:
                    break
            self.longest_length = max(current_length, self.longest_length)

        return self.longest_length


if __name__ == '__main__':
    sol = Solution()
    print(sol.longestConsecutive([100, 4, 200, 1, 3, 2]))
    print(sol.longestConsecutive([0, 3, 7, 2, 5, 8, 4, 6, 0, 1]))