php 递归无线级别分类

 <meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
 <?php
 $tree=array(
     array('id'=>1,'name'=>'安徽','pid'=>'0'),
     array('id'=>2,'name'=>'北京','pid'=>'0'),
     array('id'=>3,'name'=>'山东','pid'=>'0'),
     array('id'=>4,'name'=>'昭阳区','pid'=>'2'),
     array('id'=>5,'name'=>'合肥市','pid'=>'1'),
     array('id'=>6,'name'=>'蜀山区','pid'=>'5'),
     array('id'=>7,'name'=>'烟台市','pid'=>'3'),
     );
 /**
  * @param $data array
  * @param $pid parent_id
  * @param $level
  * @author tian
  */
 function tree($data,$pid=0,$level=1){
     static $arr=array();
     foreach($data as $v){
         if($v['pid']==$pid){
             $v['level']=$level;
             $arr[]=$v;
             tree($data,$v['id'],$level+1);
         }
     }
 return $arr;
 }

 $list=tree($tree,0,1);
 var_dump($list);
  ?>