using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

​

    public class DLinkedList

   {

        public class DLinkedNode 

        {

​

            public object _sync = new Object();

            public object _syncup = new Object();

            public DLinkedNode next;

            public DLinkedNode prev;

            public int data;

            public DLinkedNode(int value)

            {

                data = value;

                next = null;

                prev = null;

            }

            public void run()

            {

                SentX();

            }

            private void SentX()

            {

                if(next != null)

                    next.ReceiveX(data);

                if(prev != null)

                    prev.ReceiveX(data);

            }

            public void ReceiveX(int x)

            {

                lock(_syncup)

                {

                    data += x;

                }

            }

        } 

      private DLinkedNode head;

      public DLinkedList()

      {

         head = null;

      }

      public void InsertNext(int value)

      {

            DLinkedNode node = new DLinkedNode(value);

            if(head == null)

            {

                  head = node;

            }

            else

            {

                DLinkedNode tmp = head;

                while(tmp.next != null)

                {

                  tmp = tmp.next;

                }

                node.prev = tmp;

                tmp.next = node;

            }

      }

      public void Traverse()

      {

         Traverse(head);

      }

      public void Traverse(DLinkedNode node)

      {

            Console.WriteLine("\n\nTraversing in Forward Direction\n\n");

            while(node != null)

            {

                  System.Console.WriteLine(node.data);

                  node = node.next;

            }

      }

        public void Run()

        {

            DLinkedNode tmp = head;

            while(tmp != null)

            {

                lock(tmp._sync)

                {

                    tmp.run();

                }

                tmp = tmp.next;

            }

            //Traverse();

        }

    }

public class Program

{

    public static void Main()

    {

        DLinkedList list = new DLinkedList();

        list.InsertNext(1);

        list.InsertNext(2);

        list.InsertNext(3);

        list.InsertNext(4);

        list.Traverse();

        list.Run();

        list.Traverse();

    }

}