无限极分类

function generateTree($data){
    $items = array();
    foreach($data as $v){
        $items[$v['auth_id']] = $v;
    }
    $tree = array();
    foreach($items as $k => $item){
    //用遍历每一项的pid来判别，判别$item这条数据有上级，且上级为id为pid的这条数据，当前的key应该为item这条数据的id
        if(isset($items[$item['auth_pid']])){
            $items[$item['auth_pid']]['son'][] = &$items[$k];
        }else{
            $tree[] = &$items[$k];
        }
    }
    return $tree;
}
id       pid
116      100
200      116
234      200
$tree[0]=&$items[116]
$items[$item['auth_pid']]['son'][] = &$items[$k];
$items[116]['son'][0]=&items[200]
$items[200]['son'][0]=&items[234]

无限极分类

来源：https://www.cnblogs.com/mofei12138/p/12294475.html