Longest Consecutive Sequence 🔍

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.

🤔 Examples 🤔

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