void copy_list(const node*& source_ptr, node*& dest_ptr)
{
	const node* current = source_ptr;
	node* copy = new node();
	node* last = copy;
	dest_ptr = copy;

	copy->data = current->data;
	current = current->next;

	while (current != nullptr)
	{
		last->next = new node();
		last = last->next;

		last->data = current->data;
		current = current->next;
	}
	last->next = nullptr;
}