LC128. Longest Consecutive Sequence

class Solution:
    def longestConsecutive(self, nums: List[int]) -> int:
        if len(nums) == 0:
            return 0
        
        nums_set = set(nums)
 
        longest = 1
        for num in nums_set:
            if num - 1 in nums_set:
                continue
            
            length = 1
            while num + 1 in nums_set:
                length += 1
                num += 1
            
            longest = max(length, longest)
 
        return longest

Complexity

Time: $O(n)$
Space: $O(n)$

Categories

Hashset