Given a 2D matrix of size M*N. Traverse and print the matrix in spiral form.

spiral.php

<?php
    $arr = array(array(1,2,3,4),array(5,6,7,8),array(9,10,11,12),array(13,14,15,16));
    $k = 0;
    $m = 3;//last row
    $l = 0;
    $n = 3; //last column
    
    while($k <= $m && $l <= $n){
        for($i=0;$i<=$m;$i++){
            echo $arr[$k][$i];
        }
        $k++;
        for($i=$k;$i<=$n;$i++){
            echo $arr[$i][$n];
        }
        $n--;
        if($k <= $m){
            for($i=$n;$i>=$l;$i--){
                echo $arr[$m][$i];
            }
        $m--;
        }
        if($l <= $n){
            for($i=$m;$i>=$k;$i--){
                echo $arr[$i][$l];
            }
            $l++;
        }
    }
?>