Hackerrank challenge - Diagonal Difference - https://www.hackerrank.com/challenges/diagonal-difference/problem

diagonal-difference.php

function diagonalDifference($arr) {
    $diagAc = [];
    $diagBd = [];
    $arrMain_len = count($arr);
    
    foreach ($arr as $key => $arrSub) {
        $arrSub_len = count($arrSub);
        
        if ($arrMain_len == $arrSub_len) {
            $diagAc[] = $arrSub[$key];
            $diagBd[] = $arrSub[$arrMain_len - $key - 1];
        } else {
            throw new Exception("This isn't square!");
        }
    }

    $result = abs(array_sum($diagAc) - array_sum($diagBd));

    return $result;
}