如何在PHP中从关联数组构建多维数组树？

function buildTree($array, $parentId = 0) {
    $tree = array();
    
    foreach ($array as $item) {
        if ($item['parent_id'] == $parentId) {
            $children = buildTree($array, $item['id']);
            
            if (!empty($children)) {
                $item['children'] = $children;
            }
            
            $tree[] = $item;
        }
    }
    
    return $tree;
}

// 示例关联数组
$array = array(
    array('id' => 1, 'name' => 'Node 1', 'parent_id' => 0),
    array('id' => 2, 'name' => 'Node 2', 'parent_id' => 0),
    array('id' => 3, 'name' => 'Node 1.1', 'parent_id' => 1),
    array('id' => 4, 'name' => 'Node 1.2', 'parent_id' => 1),
    array('id' => 5, 'name' => 'Node 2.1', 'parent_id' => 2),
    array('id' => 6, 'name' => 'Node 2.2', 'parent_id' => 2),
    array('id' => 7, 'name' => 'Node 1.1.1', 'parent_id' => 3),
);

$tree = buildTree($array);
print_r($tree);

Array
(
    [0] => Array
        (
            [id] => 1
            [name] => Node 1
            [parent_id] => 0
            [children] => Array
                (
                    [0] => Array
                        (
                            [id] => 3
                            [name] => Node 1.1
                            [parent_id] => 1
                            [children] => Array
                                (
                                    [0] => Array
                                        (
                                            [id] => 7
                                            [name] => Node 1.1.1
                                            [parent_id] => 3
                                        )
                                )
                        )
                    [1] => Array
                        (
                            [id] => 4
                            [name] => Node 1.2
                            [parent_id] => 1
                        )
                )
        )
    [1] => Array
        (
            [id] => 2
            [name] => Node 2
            [parent_id] => 0
            [children] => Array
                (
                    [0] => Array
                        (
                            [id] => 5
                            [name] => Node 2.1
                            [parent_id] => 2
                        )
                    [1] => Array
                        (
                            [id] => 6
                            [name] => Node 2.2
                            [parent_id] => 2
                        )
                )
        )
)