Pairs

Language : Python 2

(NOTE : Try a few times yourself before moving to the solution)

#!/bin/python

import math
import os
import random
import re
import sys

#
# Complete the 'pairs' function below.
#
# The function is expected to return an INTEGER.
# The function accepts following parameters:
#  1. INTEGER k
#  2. INTEGER_ARRAY arr
#

def pairs(k, arr):
    return len(set(arr) & set([item + k for item in set(arr)]))

if __name__ == '__main__':
    fptr = open(os.environ['OUTPUT_PATH'], 'w')

    first_multiple_input = raw_input().rstrip().split()

    n = int(first_multiple_input[0])

    k = int(first_multiple_input[1])

    arr = map(int, raw_input().rstrip().split())

    result = pairs(k, arr)

    fptr.write(str(result) + '\n')

    fptr.close()