using System;

​

public class Program

{

    public Node head;

    public class Node

    {

        public int data;

        public Node next;

        public Node(int d)

        {

            data = d;

            next = null;

        }

    }

​

    public void AddNode(int d)

    {

        Node new_node = new Node(d);

        new_node.next = head;

        head = new_node;

    }

​

    public void PrintList()

    {

        Node tnode = head;

        while (tnode != null)

        {

            Console.Write("{0}->,", tnode.data);

            tnode = tnode.next;

        }

    }

​

    public int Detectloop()

    {

        Node slow = head;

        Node fast = head;

        slow = slow.next;

        fast = fast.next.next;

        while (fast != null && fast.next != null)

        {

            if (slow.next.data == fast.next.data)

            {

                return fast.data;

            }

​

            fast = fast.next;

        }

​

        return -99;

    }

​

    public void Deleteloop()

    {

        Node slow = head;

        Node fast = head;

        slow = slow.next;

        fast = fast.next.next;

        while (fast != null && fast.next != null)

        {

            if (slow.next.data == fast.next.data)

            {

                fast.next = null;

                break;

            }

​

            fast = fast.next;

        }

    }

​

    public void Printloop(int key)

    {

        if (key == -99)

        {

            Console.WriteLine("No loop");

        }

        else

        {

            Console.WriteLine("Loop detected at {0},", key);

        }

    }

​

    public static void Main()

    {

        Program p = new Program();

        int[] list = new int[]{1, 2, 3, 4, 5};

        for (int i = 0; i < list.Length; i++)

        {

            p.AddNode(list[i]);

        }

​

        p.PrintList();

        p.head.next.next.next.next.next = p.head.next.next;

        int key = p.Detectloop();

        Console.WriteLine();

        p.Printloop(key);

        p.Deleteloop();

        p.PrintList();

        int keys = p.Detectloop();

        Console.WriteLine();

        p.Printloop(keys);

    }

}