Hacker Rank Problem Solving in PHP - Diagonal Difference

HackerRank Problem Solving - A Very Big Sum

Given a square matrix, calculate the absolute difference between the sums of its diagonals.

For example, the square matrix arr is shown below:

1 2 3
4 5 6
9 8 9  

The left-to-right diagonal 1 + 5 + 9 = 15. The right to left diagonal 3 + 5 + 9 = 17. Their absolute difference is |15 - 17| = 2.

Function description

Complete the diagonalDifference function in the editor below.

diagonalDifference takes the following parameter:

• int arr[n][m]: an array of integers

Return

• int: the absolute diagonal difference

Solution in PHP:

<?php
/*
* Complete the 'diagonalDifference' function below.
*
* The function is expected to return an INTEGER.
* The function accepts 2D_INTEGER_ARRAY arr as parameter.
*/

function diagonalDifference($arr) {
// Write your code here
   $firstSum = 0;
   $secondSum = 0;
   $n = count($arr);

   for ($i = 0; $i < $n; $i++) {
      $firstSum += $arr[$i][$i];
      $secondSum += $arr[$i][$n - 1 - $i];
   }

   return abs($firstSum - $secondSum);
}

$fptr = fopen(getenv("OUTPUT_PATH"), "w");
$n = intval(trim(fgets(STDIN)));
$arr = array();

for ($i = 0; $i < $n; $i++) {
   $arr_temp = rtrim(fgets(STDIN));
   $arr[] = array_map('intval', preg_split('/ /', $arr_temp, -1, PREG_SPLIT_NO_EMPTY));
}

$result = diagonalDifference($arr);
fwrite($fptr, $result . "\n");
fclose($fptr);