Divisible Sum Pairs

You are given an array of  integers, , and a positive integer, . Find and print the number of  pairs where  and  +  is divisible by .

For example,  and . Our three pairs meeting the criteria are  and .

Function Description

Complete the divisibleSumPairs function in the editor below. It should return the integer count of pairs meeting the criteria.

divisibleSumPairs has the following parameter(s):

• n: the integer length of array 
• ar: an array of integers
• k: the integer to divide the pair sum by

Input Format

The first line contains  space-separated integers,  and .
The second line contains  space-separated integers describing the values of .

Constraints

Output Format

Print the number of  pairs where  and  +  is evenly divisible by .

Sample Input

6 3
1 3 2 6 1 2

Sample Output

 5

Explanation

Here are the  valid pairs when :

Hackerrank

 php

<?php

// Complete the divisibleSumPairs function below.

function divisibleSumPairs($n, $k, $ar) {

$counter = 0;

for($i = 0; $i < $n - 1; $i++) {

for($j = $i + 1; $j < $n ; $j++) {

if(($ar[$i] + $ar[$j]) % $k == 0) {

$counter++;

}

}

}

return $counter;

}

$fptr = fopen(getenv("OUTPUT_PATH"), "w");

$stdin = fopen("php://stdin", "r");

fscanf($stdin, "%[^\n]", $nk_temp);

$nk = explode(' ', $nk_temp);

$n = intval($nk[0]);

$k = intval($nk[1]);

fscanf($stdin, "%[^\n]", $ar_temp);

$ar = array_map('intval',

preg_split('/ /', $ar_temp, -1, PREG_SPLIT_NO_EMPTY));

$result = divisibleSumPairs($n, $k, $ar);

fwrite($fptr, $result . "\n");

fclose($stdin);

fclose($fptr);