Random n product to category #Magento, #Category, #Product, #CreateData

MAGENTO - add Random product to category.php

<?php

$addRamdomProductToCategory = function($n, $arrCategoryId) {
    Mage::app()->setCurrentStore(Mage_Core_Model_App::ADMIN_STORE_ID);
    $productModel = Mage::getModel('catalog/product');
    $productIds = Mage::getModel('catalog/product')->getCollection()->getAllIds();


    foreach($arrCategoryId as $catId) {
        $arrProductIdIndexs = array_rand($productIds, $n);

        foreach($arrProductIdIndexs as $index) {
            $productObj = $productModel->load($productIds[$index]);
            $productObj->setCategoryIds(array($catId));

            $productObj->setIsMassupdate(true);
            $productObj->setExcludeUrlRewrite(true);

            $productObj->save();
        }
    }
};
$addRamdomProductToCategory(20, $arrCategoryId);