要解决你的问题，你需要正确地理解如何的变量引用/别名在PHP 工作。

To solve your problem you need to properly understand how variable referencing/aliasing in PHP works.

请看下面的例子code，它不看你要多大不同，但利用引用才能访问，即使它已经搬任何父母：

Look at the following example code, which does not look much different to yours but makes use of references in order to access any parent even it has already "moved":

# transform $flat into a tree:
foreach($flat as $id => &$value)
{
    # check if there is a parent
    if ($parentId = $value['parent'])
    {
        $flat[$parentId][0][$id] =& $value; # add child to parent
        unset($flat[$id]); # remove reference from topmost level
    }
}
unset($value); # remove iterator reference
print_r($flat); # your tree

$平现在包含 $平所有值 - 但重新排序。 演示。

$flat now contains all values from $flat - but reordered. Demo.