Given an unsorted array of integers, return the length of the longest consecutive sequence. Sorting makes consecutive values adjacent, so the longest run can be counted in one scan.
nums = array of integers
length of the longest consecutive sequence
Example 1:
Input:
nums = [100,4,200,1,3,2]
Output:
4
Explanation:
The longest consecutive sequence is [1,2,3,4].
Example 2:
Input:
nums = [0,3,7,2,5,8,4,6,0,1]
Output:
9
Explanation:
The sequence [0..8] has length 9.