虽然@wizards answer 有效，但我觉得我想制作一个代码更清晰的版本。下面的版本返回一个带有链接和未加线元素的对象，我相信它是如何工作的非常清楚。
我想这样工作的原因是能够为将来的问题扩展它。比如“一个项目链接了多少次”或“哪个链接最多”。它也可以很容易地适应这些问题。
另一个好处是它尽可能使用有限的循环，当大小增加时，这可以加快速度。
<?php
error_reporting(E_ALL);
$obj_array = [] ;
$obj = new stdClass;
$obj->id = 1;
$obj->name = "Apple";
$obj->link = array(14, 5);
$obj_array[] = $obj;
$obj = new stdClass;
$obj->id = 3;
$obj->name = "Carrot";
$obj->link = array(1, 14, 3);
$obj_array[] = $obj;
$obj = new stdClass;
$obj->id = 4;
$obj->name = "Dill";
$obj->link = array(1, 5);
$obj_array[] = $obj;
$obj = new stdClass;
$obj->id = 5;
$obj->name = "Egg";
$obj->link = array(6);
$obj_array[] = $obj;
$obj = new stdClass;
$obj->id = 6;
$obj->name = "Fred";
$obj->link = array(7);
$obj_array[] = $obj;
$obj = new stdClass;
$obj->id = 7;
$obj->name = "Goat";
$obj->link = array(7, 8);
$obj_array[] = $obj;
$obj = new stdClass;
$obj->id = 8;
$obj->name = "Harry";
$obj_array[] = $obj;
$obj = new stdClass;
$obj->id = 9;
$obj->name = "Igloo";
$obj->link = array(14, 5);
$obj_array[] = $obj;
$obj = new stdClass;
$obj->id = 10;
$obj->name = "Jason";
$obj->link = array(1, 5, 8);
$obj_array[] = $obj;
$obj = new stdClass;
$obj->id = 11;
$obj->name = "Klaus";
$obj->link = array(1, 5, 10);
$obj_array[] = $obj;
$obj = new stdClass;
$obj->id = 14;
$obj->name = "Banana";
$obj->link = array(3);
$obj_array[] = $obj;
$obj = new stdClass;
$obj->id = 15;
$obj->name = "Oyster1";
$obj->link = array(16);
$obj_array[] = $obj;
$obj = new stdClass;
$obj->id = 16;
$obj->name = "Oyster2";
$obj->link = array(15);
$obj_array[] = $obj;
/*
* CALL
*/
$parser = new ObjectLinker($obj_array, 1);
//dump found
//decode/encode to only show public values
print_r(json_decode(json_encode($parser)));
/*
* ACTUAL CODE
*/
class ObjectLinker
{
private $_array;
private $_start;
public $LinkedElements = array();
public $UnLinkedElements = array();
final public function __construct($ar, $start)
{
$this->_array = $ar;
$this->_start = $start;
$this->getElementsArray();
$this->findLinked($this->_start);
}
final private function getElementsArray()
{
//since each Id is unique, i'm using the ID as the key in the array. this will allow faster access
//Ofcourse it would be better if you would create the array like this in the first place, then you can skip this step
foreach($this->_array as $obj) {
if (!is_null($obj) && property_exists($obj, 'id')) {
//I add everything to the unlinked elements. We will remove the linked once, to have once less loop
$this->UnLinkedElements[$obj->id] = $obj;
}
}
}
final private function findLinked($id)
{
//If the key is not in the array, it's already loaded
if (!array_key_exists($id, $this->UnLinkedElements)) {
return;
}
//get obj
//Because of the getElementsArray() step, I'm already sure the object exists.
//If you change the input array, you might want to check for invalid obj
$obj = $this->UnLinkedElements[$id];
//add to linked
$this->LinkedElements[$id] = $obj;
//remove from unlinked
unset($this->UnLinkedElements[$id]);
//no links
if (!property_exists($obj, 'link')) {
return;
}
$links = $obj->link;
//Invalid links
if (!is_array($links)) {
return;
}
//check links
foreach($links as $link) {
$this->findLinked($link);
}
}
}
?>
输出：
stdClass Object
(
[LinkedElements] => stdClass Object
(
[1] => stdClass Object
(
[id] => 1
[name] => Apple
[link] => Array
(
[0] => 14
[1] => 5
)
)
[14] => stdClass Object
(
[id] => 14
[name] => Banana
[link] => Array
(
[0] => 3
)
)
[3] => stdClass Object
(
[id] => 3
[name] => Carrot
[link] => Array
(
[0] => 1
[1] => 14
[2] => 3
)
)
[5] => stdClass Object
(
[id] => 5
[name] => Egg
[link] => Array
(
[0] => 6
)
)
[6] => stdClass Object
(
[id] => 6
[name] => Fred
[link] => Array
(
[0] => 7
)
)
[7] => stdClass Object
(
[id] => 7
[name] => Goat
[link] => Array
(
[0] => 7
[1] => 8
)
)
[8] => stdClass Object
(
[id] => 8
[name] => Harry
)
)
[UnLinkedElements] => stdClass Object
(
[4] => stdClass Object
(
[id] => 4
[name] => Dill
[link] => Array
(
[0] => 1
[1] => 5
)
)
[9] => stdClass Object
(
[id] => 9
[name] => Igloo
[link] => Array
(
[0] => 14
[1] => 5
)
)
[10] => stdClass Object
(
[id] => 10
[name] => Jason
[link] => Array
(
[0] => 1
[1] => 5
[2] => 8
)
)
[11] => stdClass Object
(
[id] => 11
[name] => Klaus
[link] => Array
(
[0] => 1
[1] => 5
[2] => 10
)
)
[15] => stdClass Object
(
[id] => 15
[name] => Oyster1
[link] => Array
(
[0] => 16
)
)
[16] => stdClass Object
(
[id] => 16
[name] => Oyster2
[link] => Array
(
[0] => 15
)
)
)
)