K-diffPairsInAnArray532.kt

package 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).
 */

fun findPairs(nums: IntArray, k: Int): Int {
    val map = HashMap<Int, Int>()
    nums.forEach { num ->
        map[num] = (map[num] ?: 0) + 1
    }

    var count = 0
    map.forEach { (key, value) ->
        if (k == 0) {
            if (value >= 2)
                count++

        } else {
            if (map.containsKey(key + k))
                count++
        }
    }
    return count
}