Circular Linked List is a variation of Linked list in which the first element points to the last element and the last element points to the first element. Both Singly Linked List and Doubly Linked List can be made into a circular linked list.
In singly linked list, the next pointer of the last node points to the first node.
In doubly linked list, 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 making the circular in both directions.
As per the above illustration, following are the important points to be considered.
The last link's next points to the first link of the list in both cases of singly as well as doubly linked list.
The first link's previous points to the last of the list in case of doubly linked list.
Following are the important operations supported by a circular list.
insert − Inserts an element at the start of the list.
delete − Deletes an element from the start of the list.
display − Displays the list.
Following code demonstrates the insertion operation in a circular linked list based on single linked list.
insertFirst(data): Begin create a new node node -> data := data if the list is empty, then head := node next of node = head else temp := head while next of temp is not head, do temp := next of temp done next of node := head next of temp := node head := node end if End
Following code demonstrates the deletion operation in a circular linked list based on single linked list.
deleteFirst(): Begin if head is null, then it is Underflow and return else if next of head = head, then head := null deallocate head else ptr := head while next of ptr is not head, do ptr := next of ptr next of ptr = next of head deallocate head head := next of ptr end if End
Following code demonstrates the display list operation in a circular linked list.
display(): Begin if head is null, then Nothing to print and return else ptr := head while next of ptr is not head, do display data of ptr ptr := next of ptr display data of ptr end if End
To know about its implementation in C programming language, please click here.