Longest Consecutive Sequence

Medium

Given an unsorted array nums, return the length of the longest run of consecutive integers. You must do it in O(n) time.

Example 1

Input:  nums = [100,4,200,1,3,2]
Output: 4
Explanation: The run [1,2,3,4] has length 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