Question

How to find the sum of boundary elements of a matrix in PHP

Answer 1

function getBoundarySum($matrix) {
    $rows = count($matrix);
    $cols = count($matrix[0]);
    $sum = 0;
    
    for ($i = 0; $i < $rows; $i++) {
        for ($j = 0; $j < $cols; $j++) {
            if ($i == 0 || $j == 0 || $i == $rows - 1 || $j == $cols - 1) {
                $sum += $matrix[$i][$j];
            }
        }
    }

    return $sum;
}

$matrix = array(array(1, 2, 3, 4), 
                array(5, 6, 7, 8), 
                array(9, 10, 11, 12));

echo getBoundarySum($matrix);




/*
run:

65

*/

 

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