Introduction To Circular Linked List With Examples

A circular linked list is a linked list where the last node links back to the first node, forming a closed loop. This structure ensures continuous traversal without a defined end, as no node points to NULL.

Types of Circular Linked Lists with Syntax

There are two types of circular linked list, let’s explain both of these

1. Singly Circular Linked List

In a singly circular linked list, each node contains data and a pointer to the next node. The next pointer of the last node points to the first node.

The singly circular linked list (with four nodes) in terms of addressing is given in the following diagram

As according to above diagram last node next address is 350 which is the address of first node.

2. Doubly Circular Linked List

In a doubly circular linked list, each node contains data, a next pointer, and a previous pointer. The next pointer of the last node points to the first node, and the previous pointer of the first node points to the last node.

The doubly circular linked list (with four nodes) in terms of addressing is given in the following diagram

Key Operations in a Circular Linked List

1. Insertion of a Node 

• Singly Circular Linked List:
  • Beginning: Update the next pointer of the new node to point to the head, and the last node’s next pointer to the new node.
  • End: Update the next pointer of the last node to point to the new node, and the new node’s next to the head.
  • Position: Traverse to the specified position, update the next pointer of the previous node to the new node, and the new node’s next to the next node.
• Doubly Circular Linked List:
  • Beginning: Update the next pointer of the new node to the head, the prev pointer to the last node, and adjust the head and last node links.
  • End: Update the next pointer of the last node to the new node, the new node’s next to the head, and adjust the prev links.
  • Position: Traverse to the position, update the next and prev pointers of adjacent nodes and the new node.

2. Deletion a Node 

• Singly Circular Linked List:
  • Beginning: Update the next pointer of the last node to the second node and set the head to the second node.
  • End: Traverse to the second-last node, update its next pointer to the head.
  • Position: Traverse to the node before the target, update its next pointer to skip the target node.
• Doubly Circular Linked List:
  • Beginning: Update the prev pointer of the head’s next node to the last node, set the next pointer of the last node to the new head.
  • End: Update the next pointer of the second-last node to the head, and the prev pointer of the head to the new last node.
  • Position: Update the next and prev pointers of adjacent nodes to exclude the target node.

3. Traversal in List

• • Singly Circular Linked List: Start from any node and follow the next pointers until returning to the starting node.
  • Doubly Circular Linked List: Start from any node and traverse forward using next pointers or backward using prev pointers until returning to the starting node.