DoublyLinkedList

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication7
{
    class Node
    {
        object _data;
        public object Data {
            get { return _data; }
            set { _data = value; }
        }

        Node _next;
        public Node Next
        {
            get { return _next; }
            set { _next = value; }
        }

        Node _prev;
        public Node Prev
        {
            get { return _prev; }
            set { _prev = value; }
        }

        public Node(object d, Node n, Node p)
        {
            Data = d;
            Next = n;
            Prev = p;
        }
    }

    class DoublyList
    {
        Node _head;
        public Node head
        {
            get { return _head; }
            set { _head = value; }
        }

        Node _tail;
        public Node tail
        {
            get { return _tail; }
            set { _tail = value; }
        }

        int _count;
        public int count
        {
            get { return _count; }
            set { }
        }

        public DoublyList()
        {
            head = null;
            tail = null;
            count = 0;
        }

        public object Add(object o)
        {
            return Add(count, o);
        }

        public object Add(int index, object o)
        {
            if (index < 0 || index > count)
            {
                throw new IndexOutOfRangeException("Az index nem lehet negatív!");
            }
            if (Empty() || index == 0)
            {
                head = new Node(o, null, null);
                tail = head;
            }
            else
            {
                if (count / 2 > index)
                {
                    Node current = head;
                    for (int i = 0; i < index - 1; i++)
                    {
                        current = current.Next;
                    }
                    Node next = current.Next;
                    current.Next = new Node(o, current.Next, current);
                    if (next != null)
                    {
                        next.Prev = current.Next;
                    }
                    else
                    {
                        tail = current.Next;
                    }
                }
                else
                {
                    Node current = tail;
                    for (int i = 0; i < index - 1; i++)
                    {
                        current = current.Prev;
                    }
                    Node prev = current.Next;
                    current.Prev = new Node(o, current.Prev, current);
                    if (prev != null)
                    {
                        prev.Next = current.Prev;
                    }
                    else
                    {
                        head = current.Prev;
                    }
                }
            }
            _count++;
            return o;
        }

        public object Remove(int index)
        {
            object x;
            if (index < 0 || index > count)
            {
                throw new IndexOutOfRangeException("Az index nem lehet negatív!");
            }
            else if (Empty() || index == 0)
            {
                x = head.Next.Data;
                head.Next = head.Next.Next;
            }
            else
            {
                Node current = head;
                for (int i = 0; i < index; i++)
                {
                    current = current.Next;
                }
                x = current.Data;
                current = current.Next;
            }
            _count--;
            return x;
        }

        public object Get(int index)
        {
            Node current = head;
            for (int i = 0; i < index - 1; i++)
            {
                current = current.Next;
            }
            return current.Next.Data;
        }

        public void Clear()
        {
            head = null;
        }

        public bool Empty()
        {
            return count == 0;
        }

        public int IndexOf(object o)
        {
            Node current = head;
            if (Empty() || o == null)
            {
                throw new Exception("");
            }
            else
            {
                for (int i = 0; i < count; i++)
                {
                    if (current.Data.Equals(o))
                    {
                        return i;
                    }
                    current = current.Next;
                }
                return -1;
            }
        }

        public bool Contains(object o)
        {
            return !(IndexOf(o) == -1);
        }
    }

    class Program
    {
        static void Main(string[] args)
        {

            DoublyList a = new DoublyList();

            a.Add(10);
            a.Add(10);
            a.Add(10);
            a.Add(10);
            a.Add(10);

            Console.WriteLine(a.Get(4));

            Console.ReadKey();
        }
    }
}