Diagonal Difference

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

For example, the square matrix  is shown below:

1 2 3
4 5 6
9 8 9  

The left-to-right diagonal = . The right to left diagonal = . Their absolute difference is .

Function description

Complete the  function in the editor below. It must return an integer representing the absolute diagonal difference.

diagonalDifference takes the following parameter:

• arr: an array of integers .

Input Format

The first line contains a single integer, , the number of rows and columns in the matrix .
Each of the next  lines describes a row, , and consists of  space-separated integers .

Constraints

Output Format

Print the absolute difference between the sums of the matrix's two diagonals as a single integer.

Sample Input

3
11 2 4
4 5 6
10 8 -12

Sample Output

15

Explanation

The primary diagonal is:

11
   5
     -12

Sum across the primary diagonal: 11 + 5 - 12 = 4

The secondary diagonal is:

     4
   5
10

Sum across the secondary diagonal: 4 + 5 + 10 = 19
Difference: |4 - 19| = 15

Note: |x| is the absolute value of x

 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

$arrDiag = count($arr);

$firstD = 0;

$secondD = 0;

$i =0;

for($j = 0; $j < $arrDiag; $j++) {

$firstD += $arr[$i++][$j];

$secondD += $arr[$arrDiag - $i][$j];

}

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);