[Leetcode] 0128. Longest Consecutive Sequence

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内容目录

Medium

Given an unsorted array of integers nums, return the length of the longest consecutive elements sequence.

You must write an algorithm that runs in O(n) time.

Example 1:

Input: nums = [100,4,200,1,3,2]
Output: 4
Explanation: The longest consecutive elements sequence is [1, 2, 3, 4]. Therefore its length is 4.

Example 2:

Input: nums = [0,3,7,2,5,8,4,6,0,1]
Output: 9

Constraints:

0 <= nums.length <= 10 ⁵
-10 ⁹ <= nums[i] <= 10 ⁹

Python

				
					from typing import List class Solution: def longestConsecutive(self, nums: List[int]) -> int: longestStreak = 0 numSet = set(nums) for num in nums: if num - 1 not in numSet: currentNum = num currentStreak = 1 while currentNum + 1 in numSet: currentNum += 1 currentStreak += 1 longestStreak = max(longestStreak, currentStreak) return longestStreak

Medium

Python

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