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## Hackerrank - Pairs Solution

Beeze Aal

You will be given an array of integers and a target value. Determine the number of pairs of array elements that have a difference equal to a target value.

For example, given an array of [1, 2, 3, 4] and a target value of 1, we have three values meeting the condition: , , and .

Function Description

Complete the pairs function below. It must return an integer representing the number of element pairs having the required difference.

pairs has the following parameter(s):

• k: an integer, the target difference
• arr: an array of integers

Input Format

The first line contains two space-separated integers  and , the size of  and the target value.
The second line contains  space-separated integers of the array .

Constraints

• each integer  will be unique

Output Format

An integer representing the number of pairs of integers whose difference is .

Sample Input

5 2
1 5 3 4 2


Sample Output

3


Explanation

There are 3 pairs of integers in the set with a difference of 2: [5,3], [4,2] and [3,1] .

### Solution in Python

def pairs(k, arr):
arr = set(arr)
return sum(1 for i in arr if i+k in arr)
n,k = map(int,input().split())
arr = list(map(int,input().split()))
print(pairs(k, arr))