Circular_Linked_List

Circular Linked List

A Circular Linked List is a linked data structure that consists of a set of sequentially linked records called nodes. Each node is connected to the next node via a link field which refences the next node in sequence. Each node consists of a data/key.

In a circular linked list all nodes are connected to form a circle. There is no NULL at the end. A circular linked list can be a singly circular linked list or doubly circular linked list.

The head or starter pointer points to the beginning of the circular linked list.

An example of a Circular linked list:

Courtesy: geeksforgeeks.org

Insert in a Circular Linked List

1. Prepend - Add node to the beginning of the list

In a prepend operation - a node is added to the beginning of the circular linked list. The newly added node becomes the head of the Circular linked list.

Circular Linked List before Prepend operation

Circular Linked List after Prepend operation

2. Append - Add node to the end of the list

In an append operation - a node is added to the end of the circular linked list. This new node after insertion points to the beginning of the circular linked list or the head.

Circular Linked List before Append operation

Circular Linked List after Append operation

3. Insert After a Given Node or In between Nodes

If the circular linked list is empty - a node can be added via an append operation to create a new circular linked list with a single item.

Otherwise we traverse the list and the new node is added after the given node.

Circular Linked List before Insert - New node between nodes

Circular Linked List after Insert - New node between nodes

Courtesy: geeksforgeeks.org

Delete in a Circular Linked List

Case 1. Delete head in a single element circular linked list

Deletes the only element and no circular linked list remains.

Circular linked list before deletion of head

Circular linked list after deletion of the only node in the list

Case 2. Delete head in a circular linked list with more than one element

List with more than one element and then deleting head

Case 3. Delete a middle node

List with more than one element and then deleting a middle node

Case 4. Delete the last node

Delete the last node in a circular linked list

Courtesy: geeksforgeeks.org

See also

• Wikipedia : Circular Linked List
• GeeksForGeeks : Circular Linked List Introduction
• GeeksForGeeks : Circular Linked List Insertion
• GeeksForGeeks : Circular Linked List Deletion