递归无限极分类

<?php
header("Content-Type:text/html;charset=UTF-8");
echo "<pre>";
$area = array(
array('id'=>1,'area'=>'北京','pid'=>0),
array('id'=>2,'area'=>'广西','pid'=>0),
array('id'=>3,'area'=>'广东','pid'=>0),
array('id'=>4,'area'=>'福建','pid'=>0),
array('id'=>11,'area'=>'朝阳区','pid'=>1),
array('id'=>12,'area'=>'海淀区','pid'=>1),
array('id'=>21,'area'=>'南宁市','pid'=>2),
array('id'=>45,'area'=>'福州市','pid'=>4),
array('id'=>113,'area'=>'亚运村','pid'=>11),
array('id'=>115,'area'=>'奥运村','pid'=>11),
array('id'=>234,'area'=>'武鸣县','pid'=>21)
);

function digui($arr,$pid=0,$lev=0){
$list = array();
foreach($arr as $v){
if($v['pid']==$pid){
echo $v['html'] = str_repeat("----",$lev).$v['area']."<br/>";
$list[]= $v;
digui($arr,$v['id'],$lev+1);
}
}
return $list;
}

$list =digui($area);
echo "<hr/>";
print_r($list);