get path of Array (PHP)

Question

i have an array input like this ..

Array
(
    [0] => Array
        (
            [0] => 42
        )

    [**42**] => Array
        (
            [0] => 12
            [1] => 14
        )

    [**14**] => Array
        (
            [0] => 317
        )

    [317] => Array
        (
            [0] => 319
        )

    [**12**] => Array
        (
            [0] => 306
            [1] => 307
        )

    [307] => Array
        (
            [0] => 311
        )

    [306] => Array
        (
            [0] => 309
        )
)

and i want to get result array like bellow :

$paths[]=array(42,12,306,309);

$paths[]=array(42,12,307,311);

$paths[]=array(42,14,317,319);

see array input

• root in array input = 42 (index of array 0)
• 42 have child = 12, 14
• 12 have child = 306, 307
• 14 have child = 317
• 306 have child = 309
• 307 have child = 311
• 317 have child = 319

like this..

and output array insert into $paths

$paths[0]=array(42,12,306,309);

$paths[1]=array(42,12,307,311);

$paths[2]=array(42,14,317,319);

Answer 1

This should do the trick:

function getpaths($arr, $node = 0){
    $path = array();
    foreach($arr[$node] as $next){
        if(isset($arr[$next])){
            $p = getpaths($arr, $next);
            foreach($p as $q){
                $path[] = array_merge(array($next), $q);
            }
        }else{
            $path[] = array($next);
        }
    }
    return $path;
}

Invoke as $path = getpaths($arr);

Answer 2

this is coding by Mark E, and i add one line coding to solve "Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 24 bytes)"

like this...

function getpaths($arr, $node = 0){
    $path = array();
    foreach($arr[$node] as $next){
        if(isset($arr[$next])){
            $node = $next;// adding by me
            $p = getpaths($arr, $node);
            foreach($p as $q){
                $path[] = array_merge(array($next), $q);
            }
        }else{
            $path[] = array($next);
        }
    }
    return $path;
}

thanks Mark E