Print array in spiral

gistfile1.php

<?php
// $a[0] = [ 1,  2,  3,  4]
// $a[1] = [ 5,  6,  7,  8]
// $a[2] = [ 9, 10, 11, 12]
// $a[3] = [13, 14, 15, 16]

// 1 2 3 4 8 12 11 10 9 5 6 7

/*
0,0 3,2
1,1 2,1
2,2 1,0 <- doesn't make sense

additional row:

0,0 3,3
1,1 2,2
2,2 1,1 <- doesn't make sense


*/


// NOTE: ADD SPACES
function printSpiral($array) 
{
    printSpiralHelper($array, 0, count($array[0])-1, 0, count($array) -1); // array, 0, 0, 0, 1
}

function printSpiralHelper($array, $x1, $x2, $y1, $y2) {
    // Single element
    if ($x2 == $x1 && $y2 == $y1) {
        echo $array[$y1][$x1];
        return;
    }
    // Overlap
    else if ($x2 < $x1 || $y2 < $y1) 
        return;
    
    // top row
    $i = $x1;
    for (; $i <= $x2; $i++) {
        echo $array[$y1][$i];
    }
    
    // right col
    $j = $y1+1;
    for (; $j <= $y2; $j++ ) {
        echo $array[$j][$i];
    }
    
    // bottom row backwards
    $i1 = $i-1;
    for (; $i1 >= $x1; $i1--) {
        echo $array[$j][$i1];
    }
    
    // left col upwards
    $k = $y2-1;
    for (; $k > $y1; $k--) {
        echo $array[$k][$y1];
    } 
    
    printSpiralHelper($array, $x1+1, $x2-1, $y1+1, $y2-1);   
}
?>