简单代码实现无限分类树

$items = array(  

    1 => array('id' => 1, 'pid' => 0, 'name' => '江西省'),  

    2 => array('id' => 2, 'pid' => 0, 'name' => '黑龙江省'),  

    3 => array('id' => 3, 'pid' => 1, 'name' => '南昌市'),  

    4 => array('id' => 4, 'pid' => 2, 'name' => '哈尔滨市'),  

    5 => array('id' => 5, 'pid' => 2, 'name' => '鸡西市'),  

    6 => array('id' => 6, 'pid' => 4, 'name' => '香坊区'),  

    7 => array('id' => 7, 'pid' => 4, 'name' => '南岗区'),  

    8 => array('id' => 8, 'pid' => 6, 'name' => '和兴路'),  

    9 => array('id' => 9, 'pid' => 7, 'name' => '西大直街'),  

    10 => array('id' => 10, 'pid' => 8, 'name' => '东北林业大学'),  

    11 => array('id' => 11, 'pid' => 9, 'name' => '哈尔滨工业大学'),  

    12 => array('id' => 12, 'pid' => 8, 'name' => '哈尔滨师范大学'),  

    13 => array('id' => 13, 'pid' => 1, 'name' => '赣州市'),  

    14 => array('id' => 14, 'pid' => 13, 'name' => '赣县'),  

    15 => array('id' => 15, 'pid' => 13, 'name' => '于都县'),  

    16 => array('id' => 16, 'pid' => 14, 'name' => '茅店镇'),  

    17 => array('id' => 17, 'pid' => 14, 'name' => '大田乡'),  

    18 => array('id' => 18, 'pid' => 16, 'name' => '义源村'),  

    19 => array('id' => 19, 'pid' => 16, 'name' => '上坝村'),  

    20 => array('id' => 20, 'pid' => 0, 'name' => '广东省'),  

    21 => array('id' => 21, 'pid' => 20, 'name' => '广州市'),  

);  

  

$t = array();  

foreach ($items as $id => $item) {  

    if ($item['pid']) {  

        $items[$item['pid']][$item['id']] = &$items[$item['id']];  

        $t[] = $id;  

    }  

}  

  

foreach($t as $u) {  

    unset($items[$u]);  

}  

echo "<pre>";  

print_r($items);