Given a list of integers nums and an integer k, return the k-th (0-indexed) smallest abs(x - y) for every pair of elements (x, y) in nums. Note that (x, y) and (y, x) are considered the same pair.
n ≤ 100,000 where n is the length of nums
Here are all the pair distances:
Sorted in ascending order we have [1, 1, 2, 2, 3, 4].