php实现由内向外回环

前几天一个同事面试，让写一个由内向外回环，现代码为

<?php
	
	function printNumbers($n){
    $y = $x = ($n - 1) / 2;
    $num = 2;
    $total = pow($n, 2);
    $arr = array_fill(0, $n, array_fill(0, $n, 1));
    $i = 0;
    $limit = 1;

    while ($num <= $total) {
        for ($j = 0; $num <= $total && $j < $limit; ++$j) {
            switch ($i) {
                case 0 :
                    ++$y;
                    break;
                case 1 :
                    ++$x;
                    break;
                case 2 :
                    --$y;
                    break;
                case 3 :
                    --$x;
                    break;
            }
            $arr[$x][$y] = $num++;
        }
        if ($i % 2 == 1) {
            ++$limit;
        }
        $i = ($i + 1) % 4;
    }
//    return $arr;
//    print_r($arr);
    for ($i = 0; $i < $n; $i ++) {
        foreach ($arr[$i] as $item) {
            if ($item < 10) {
                $item = $item . " ";
            }
            echo "  " . " $item " . "  ";
        }
        echo "</br>";
    }
}