0532. K-diff Pairs in an Array

https://leetcode.com/problems/k-diff-pairs-in-an-array

Description

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).

Example 4:

**Input:** nums = [1,2,4,4,3,3,0,9,2,3], k = 3
**Output:** 2

Example 5:

**Input:** nums = [-1,-2,-3], k = 1
**Output:** 2

Constraints:

• 1 <= nums.length <= 104

• -107 <= nums[i] <= 107

• 0 <= k <= 107

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