Correct conversion function from C# to PHP

Question

there is a function in C# (the main task of the function with an example ) :

Int32[] Spiral_Min(Int32[, ] arr) {
    List <Int32> list = new List <Int32> ();
    Int32 n = arr.GetLength(0);
    Int32 count = n;
    Int32 value = -n;
    Int32 sum = -1;
    do {
        value = -1 * value / n;
        for (Int32 i = 0; i < count; i++) {
            sum += value;
            list.Add(arr[sum / n, sum % n]);
        }
        value *= n;
        count--;
        for (Int32 i = 0; i < count; i++) {
            sum += value;
            list.Add(arr[sum / n, sum % n]);
        }
    } while (count > 0);
    return list.ToArray();
}

I'm trying to do the same in PHP, but i ran into a problem in the code, there is a string:

arr[sum / n, sum % n]

I do not understand how to do this in PHP, tried it through array_merge , but the function still doesn't work.

function f($a)
{
    $n = count($a[0]);
    $count = $n;
    $value = -$n;
    $sum = -1;

    do
    {
        $value = -1 * $value / $n;

        for ($i = 0; $i < $count; $i++) {
            $sum += $value;
            $r[] = array_merge($a[$sum / $n], $a[$sum % $n]);
        }

        $value *= $n;
        $count--;

        for ($i = 0; $i < $count; $i++) {
            $sum += $value;
            $r[] = array_merge($a[$sum / $n], $a[$sum % $n]);
        }
    }
    while ($count > 0);

    return $r;
}

Please tell me what the problem is and how to do it right?

Answer 1

Assuming $arr is a two dimensional array, you can access elements from the arrays using $arr[$index1][$index2] notation. Thus:

arr[sum / n, sum % n]

Would become:

$arr[$sum / $n][$sum % $n]

Answer 2

You can use array_push. Like below:

function f($a)
{
    $n = count($a);
    $count = $n;
    $value = -$n;
    $sum = -1;
    $r = [];
    do
    {
        $value = -1 * $value / $n;
        for ($i = 0; $i < $count; $i++) {
            $sum += $value;
            array_push($r, $a[$sum / $n], $a[$sum % $n]);
        }
        $value *= $n;
        $count--;

        for ($i = 0; $i < $count; $i++) {
            $sum += $value;
            array_push($r, $a[$sum / $n], $a[$sum % $n]);
        }
    }
    while ($count > 0);
    return $r;
}