php實現無限級分類

1. 數據
2. 遞歸實現
3. 引用實現

遞歸實現：
$arr = [
	0=>[
			'id'      =>1
			'pid'     =>0,
			'name'=>'人員管理'
	],
	1=>[
		'id'      =>2
		'pid'     =>1,
		'name'=>'人員添加'
	],
	2=>[
		'id'      =>3
		'pid'     =>2,
		'name'=>'人員XX'		
	]	
];
function getTree($pid,$arr){
	$treeArr = [];
	foreach($arr as $k=>$v){
		if($v['pid']==$pid){
			$v['child'] = getTree($v['id'],$arr);	
		}
		$treeArr[] = $v;
	}
}
getTree(0,$arr);
引用實現:
function getTree($arr){
	$itemArr = [];
	foreach($arr as $k=>$v){
		$itemArr[$v['id']] = $v;
	}
	$treeArr = [];
	foreach($itemArr as $k=>$v){
		if(isset($itemArr[$v['pid']])){
			$itemArr[$v['pid']]['child'] = &$v;
		}else{
			$treeArr[] = &$v;
		}
	}
}