128. Longest Consecutive Sequence

https://leetcode.com/problems/longest-consecutive-sequence/

Python

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

        return ans