Chapter 3, Problem 33C

Initial consideration:

While the circularly liked list implementation has to be provided using inheritance in such a way that a DoublyLinkedList class inherits from the existing CircularlyLinkedList, and the DoublyLinkedList.Node nested class inherits from CircularlyLinkedList.Node.

The following consideration has to be made before implementation:

• A circular version of a doubly linked list has to be implemented that is not having any sentinels that can generally supports the public behaviors of the original and new update methods.
• The implemented circular doubly linked list should have method called rotate() which is used to rotate the linked list counter clockwise and rotateBackward() method that can support the  public behaviors of the linked list.
• There is no need to use the sentinel nodes which are more generally useful with linked list implementation that helps to maintain the reference of all nodes of a doubly linked list.
• The node in the circular version of doubly linked list maintains two references with the previous and the next node in the doubly linked list.

Doubly-linked list:

• Doubly-linked list is a kind of data structure in which every node in the list has two link pointers where one link is pointing to previous node and the link will point to the next node in the list.
• The first node in the linked list generally points to a Null pointer and the next link of the last node in the linked list is pointing to the Null.

CircularlyLinkedList:

• Circular Linked List is also a kind of data structure where all the nodes in the list are in the formed of a circular fashion.
• The circular pattern can be a singly or doubly linked list. Unlike doubly linked list there is no Null pointer in the circular linked list. The nodes are added and removed based on the constant time factor.
• The main advantage of circular linked list is the ability to traverse the nodes of the linked list.

Inheritance:

• In object-oriented programming (OOP) inheritance is a procedure to create new class from an existing class which is known as base class or super class and the inherited class is known as derived class or sub class and the new class will inherits all the properties of the existing parent class.