public class Solution
extends Object
532 - K-diff Pairs in an Array\.
Medium
Given an array of integers `nums` and an integer `k`, return _the number of **unique** k-diff pairs in the array_.
A **k-diff** pair is an integer pair `(nums[i], nums[j])`, where the following are true:
* `0 <= i < j < nums.length`
* `|nums[i] - nums[j]| == k`
**Notice** that `|val|` denotes the absolute value of `val`.
**Example 1:**
**Input:** nums = [3,1,4,1,5], k = 2
**Output:** 2
**Explanation:** There are two 2-diff pairs in the array, (1, 3) and (3, 5). Although we have two 1s in the input, we should only return the number of **unique** pairs.
**Example 2:**
**Input:** nums = [1,2,3,4,5], k = 1
**Output:** 4
**Explanation:** There are four 1-diff pairs in the array, (1, 2), (2, 3), (3, 4) and (4, 5).
**Example 3:**
**Input:** nums = [1,3,1,5,4], k = 0
**Output:** 1
**Explanation:** There is one 0-diff pair in the array, (1, 1).
**Constraints:**
* 1 <= nums.length <= 104
* -107 <= nums[i] <= 107
* 0 <= k <= 107