Medium

Quiz

#532 K-diff Pairs in an Array

APPROACH

Given an integer array nums and a non-negative integer k, return the count of unique pairs (nums[i], nums[j]) satisfying all of the following:

- 0 <= i, j < nums.length

- i != j

- |nums[i] - nums[j]| == k

Here |val| denotes absolute value.

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).

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What is the optimal approach for this problem?