using System;

​

public class CircularLinkedList

{

    Node head;

    public class Node

    {

        public int data;

        public Node next;

        public Node(int val)

        {

            data = val;

            next = null;

        }

    }

​

    private void addAtFront(int key)

    {

        Node newNode = new Node(key);

        if (head == null)

        {

            head = newNode;

            head.next = head;

            return;

        }

​

        Node lastNode = head;

        while (lastNode.next != head)

        {

            lastNode = lastNode.next;

        }

​

        lastNode.next = newNode;

        newNode.next = head;

        head = newNode;

    }

    private void deleteFromFront()

    {

        if(head == null)

        {

            Console.WriteLine("No Linked List exists");

            return;

        }

        if(head.next == head)

        {

            head = null;

            return;

        }

        Node lastNode = head;

        while(lastNode.next != head)

        {

            lastNode = lastNode.next;

        }

        lastNode.next = head.next;

        head = head.next;

    }

    private void deleteFromEnd()

    {

        if(head == null)

        {

            Console.WriteLine("No Linked List exists");

            return;

        }

        if(head.next == head)

        {

            head = null;

            return;

        }

        Node lastNode = head;

        Node prev = head;

        while(lastNode.next != head)

        {

            prev = lastNode;

            lastNode = lastNode.next;

        }

        prev.next = head;

        lastNode = null;

    }

​

    private void printLL()

    {

        if (head == null)

        {

            Console.WriteLine("No linked list exists");

            return;

        }

​

        Node cur = head;

        do

        {

            Console.Write(cur.data);

            Console.Write("-->");

            cur = cur.next;

        } while(cur != head);

​

        Console.WriteLine();

        Console.WriteLine();

    }

​

    public static void Main(String[] args)

    {

        CircularLinkedList cll = new CircularLinkedList();

        cll.printLL();

        cll.addAtFront(9);

        cll.printLL();

        cll.addAtFront(10);

        cll.printLL();

        cll.addAtFront(13);

        cll.printLL();

        cll.addAtFront(13);

        cll.printLL();

        cll.deleteFromFront();

        cll.printLL();

        cll.deleteFromEnd();

        cll.printLL();

        cll.deleteFromEnd();

        cll.printLL();

        cll.deleteFromEnd();

        cll.printLL();

        cll.deleteFromFront();

        cll.printLL();

    }

}