phpのツリー構造表示

$a = array(array(7,5),array(7,6,1),array(7,6,2,3,5),array(7,6,2,3,6));<br /><br />$root = array();<br />foreach($a as $item) {<br />  $p =& $root;<br />  foreach($item as $k) {<br />    if(!isset($p[$k])) $p[$k] = array();<br />    $p =& $p[$k];<br />  }<br />}<br />print_r($root);<br />

Array<br />(<br />    [7] => Array<br />        (<br />            [5] => Array<br />                (<br />                )<br /><br />            [6] => Array<br />                (<br />                    [1] => Array<br />                        (<br />                        )<br /><br />                    [2] => Array<br />                        (<br />                            [3] => Array<br />                                (<br />                                    [5] => Array<br />                                        (<br />                                        )<br /><br />                                    [6] => Array<br />                                        (<br />                                        )<br /><br />                                )<br /><br />                        )<br /><br />                )<br /><br />        )<br /><br />)<br /><br />