using System;

public class Program

{

    public static void Main()

    {

        var head = new LL()

            {

                data = 5,

                next = new LL()

                {

                    data = 6,

                    next = new LL()

                    {

                        data = 7,

                        next = null

                    }

                }

            };

        Console.WriteLine(head.data + " " + head.next.data + " " + head.next.next.data);

        Reverse(ref head);

        Console.WriteLine(head.data + " " + head.next.data + " " + head.next.next.data);

    }

​

    public static void Reverse(ref LL head)

    {

        var t = head;

        while(t.next != null)

        {

            Console.WriteLine("t -> " + t.data);

            LL p = t.next;

​

            Console.WriteLine("next data " + t.next.data);

            Console.WriteLine(p.next == null);

            var setInTempNext = p.next;

            Console.WriteLine("p ->" + p.data);

            Console.WriteLine("head -> " + head.data);

            p.next = head;

            head = p;           

            Console.WriteLine("head -> " + head.data);

            if(setInTempNext == null)

            {

                Console.WriteLine("tdata -> " + t.data);

                //t.next = null;

                break;

            }

            t.next = setInTempNext;

        }

​

    }

}

​

public class LL

{

    public int data;

    public LL next;

}