Count Number of Pairs With Absolute Difference K

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Description

Given an integer array nums and an integer k, return the number of pairs (i, j) where i < j such that |nums[i] - nums[j]| == k.

The value of |x| is defined as:

- x if x >= 0.

- -x if x < 0.

Example 1:

Input: nums = [1,2,2,1], k = 1

Output: 4

Explanation: The pairs with an absolute difference of 1 are:

- [1,2,2,1]

Example 2:

Input: nums = [1,3], k = 3

Output: 0

Explanation: There are no pairs with an absolute difference of 3.

Example 3:

Input: nums = [3,2,1,5,4], k = 2

Output: 3

Explanation: The pairs with an absolute difference of 2 are:

- [3,2,1,5,4]

Solution