public class Solution
extends Object
719 - Find K-th Smallest Pair Distance\.
Hard
The **distance of a pair** of integers `a` and `b` is defined as the absolute difference between `a` and `b`.
Given an integer array `nums` and an integer `k`, return _the_ kth _smallest **distance among all the pairs**_ `nums[i]` _and_ `nums[j]` _where_ `0 <= i < j < nums.length`.
**Example 1:**
**Input:** nums = [1,3,1], k = 1
**Output:** 0
**Explanation:** Here are all the pairs:
(1,3) -> 2
(1,1) -> 0
(3,1) -> 2
Then the 1st smallest distance pair is (1,1), and its distance is 0.
**Example 2:**
**Input:** nums = [1,1,1], k = 2
**Output:** 0
**Example 3:**
**Input:** nums = [1,6,1], k = 3
**Output:** 5
**Constraints:**
* `n == nums.length`
* 2 <= n <= 104
* 0 <= nums[i] <= 106
* `1 <= k <= n * (n - 1) / 2`