Understanding insertion before the given node

In linked lists, it is important to access the node before the one being inserted or deleted. In a singly linked list, finding the node before the given one requires traversing the entire list. However, in a doubly linked list, the node before the given one can be accessed directly using the previous pointer stored in each node, simplifying the operation. Let's examine the three cases we need to consider.

1. The list is empty

If the list is empty and contains no elements, we cannot find the given node because it does not exist within the list. Inserting a new node after the given node is not possible because there is no reference point within the list to perform the insertion. In such a case, we can return the head node that was provided as it is.