Diagonal Sum difference in matrice solved using PHP

 Find the difference of diagonal sum in matrice i.e., 

[1 2 3]

[4 5 6]

[7 8 9]

First diagonal is [1 5 9] and second diagonal is [3 5 7] i.e., 1st diagonal sum is 1+5+9 =15 and second diagonal sum is 3+5+7 = 15 so, difference is 0. If it is negative number it should be converted to positive.

<?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

    $n=count($arr);

    

    $firstD =0;

    $secondD=0;

    

    for($i=0;$i<$n;$i++){

        $firstD+=$arr[$i][$i];

        $secondD+=$arr[$n-$i-1][$i];

    }

    

    return abs($firstD - $secondD);

}

$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);