php rebuild words using keys of a multidimensional array

I've created a method that combine some "tiles" to find all sequences to compose a word.

<?php
/* convert word to tiles sequences */
function word2sequences($word, $tiles, &$founds = array()) {
  foreach ($tiles as $tile_id => $tile) {
    if (!preg_match("/^(|[;0-9]{1,})(".$tile.")(.*)$/i", $word, $tok)) continue;
    $found = $tok[1].";".$tile_id.";".$tok[3];
    if (!array_key_exists($word, $founds)) $founds[$tile] = array();
    $founds[$tile] = word2sequences($found, $tiles);
  }
  return $founds;
}

/* example */
$tiles = [1 => "A", 21 => "B", 34 => "AH", 40 => "R", 51 => "S", 83 => "SA", 14 => "T", 21 => "TA"];
$word = "stars";
$sequences = word2sequences($word, $tiles);
echo "<pre>";
var_dump($sequences);
?>

the output is

array(1) {
  ["S"]=>
  array(2) {
    ["TA"]=>
    array(1) {
      ["R"]=>
      array(1) {
        ["S"]=>
        array(0) {
        }
      }
    }
    ["T"]=>
    array(1) {
      ["A"]=>
      array(1) {
        ["R"]=>
        array(1) {
          ["S"]=>
          array(0) {
          }
        }
      }
    }
  }
}

so I know that to compose the word "stars" I can use the tiles "S,TA,R,S" or "S,T,A,R,S".

there is a way to walk the $requences array to extract all the sequences in a simplified format like:

$sequences = array(
  0 => array("S", "TA", "R", "S"),
  1 => array("S", "T", "A", "R", "S")
)

Tnx in advance.

source https://stackoverflow.com/questions/71237759/php-rebuild-words-using-keys-of-a-multidimensional-array