Magento :: Assign Product to parent category

<?php

define('MAGENTO_ROOT', getcwd());

include_once "app/Mage.php";

ini_set('display_errors', 1);
error_reporting(E_ALL | E_STRICT);

Mage::init();
Mage::app()->setCurrentStore(Mage_Core_Model_App::ADMIN_STORE_ID);
umask(0);
Mage::app('admin');

set_time_limit(0);
ini_set('memory_limit', '2048M');

$categoryId = Mage::app()->getRequest()->getParam('catid');

$category = Mage::getModel('catalog/category')->load($categoryId);
$allProducts = $category->getProductsPosition();

foreach ($category->getChildrenCategories() as $child) {
       $childProducts = $child->getProductsPosition();
       foreach($childProducts as $productId=>$position) {
              if(!array_key_exists($productId,$allProducts)) {
                     $allProducts[$productId] = $position; 
              }
       }
}
$category->setPostedProducts($allProducts)->save();

echo "Product Assigned successfully";

?>