WC 3.x Get categories from variable product of the cart

Ok, I resolved it.

In a variable product $_product->get_id() is not of ID the product else is the ID only of these variation at cart.

Then, in these loop can found the id of product in the variable $cart_item['product_id']

We can use it:

$the_product = wc_get_product( $cart_item['product_id'] );
$array_cat = $the_product->get_category_ids();

Regards