Write a Program to remove duplicate elements from a doubly linked list.

Solution:

using System;

namespace LinkedListOpearation
{
    class Program
    {
        public static void Main()
        {
            var dList = new DoublyLinkedList();
            dList.Add(19);
            dList.Add(82);
            dList.Add(12);
            dList.Add(19);
            dList.Add(43);

            Console.WriteLine("Doubly Linked List: ");
            dList.Print();
            dList.RemoveDuplicateNode();
            Console.WriteLine("After Removing Duplicate Element from Doubly Linked List: ");
            dList.Print();
            Console.ReadLine();
        }
    }


    public class DoublyLinkedList
    {
        public int Size;
        public Node Head;
        public Node Tail;

        public void Add(int data)
        {
            var newNode = new Node(data);

            if (Head == null)
            {
                Head = Tail = newNode;
                Head.Previous = null;
                Tail.Next = null;
            }
            else
            {
                Tail.Next = newNode;
                newNode.Previous = Tail;
                Tail = newNode;
                Tail.Next = null;
            }
            Size++;
        }

        public void RemoveDuplicateNode()
        {
            Node current;

            if (Head == null)
                return;

            for (current = Head; current != null; current = current.Next)
            {
                Node index;
                for (index = current.Next; index != null; index = index.Next)
                {
                    if (current.Data != index.Data) continue;
                    index.Previous.Next = index.Next;
                    if (index.Next != null)
                        index.Next.Previous = index.Previous;
                }
            }
        }


        public void Print()
        {
            var current = Head;
            if (Head == null)
                return;
            
            while (current != null)
            {
                Console.WriteLine(current.Data);
                current = current.Next;
            }
        }
    }

    public class Node
    {
        public int Data;
        public Node Next;
        public Node Previous;
        
        public Node(int data)
        {
            Data = data;
        }
    }
}