using System;

​

public class Program

{

    public static void Main(string[] args)

    {

        var first = new Node(10);

        var second = new Node(15);

        var third = new Node(12);

        var fourth = new Node(13);

        var fifth = new Node(20);

        var sixth = new Node(14);

        first.Next = second;

        second.Next = third;

        third.Next = fourth;

        fourth.Next = fifth;

        fifth.Next = sixth;

        first.Print();

        Swap(ref first, 10, 14);

        Console.WriteLine("=============== After swapping ===============");

        first.Print();

    }

​

    static void Swap(ref Node head, int data1, int data2)

    {

        Node prev1 = null, prev2 = null, node1 = head, node2 = head;

        if (data1 == data2)

        {

            return;

        }

​

        while (node1 != null && node1.Data != data1)

        {

            prev1 = node1;

            node1 = node1.Next;

        }

​

        while (node2 != null && node2.Data != data2)

        {

            prev2 = node2;

            node2 = node2.Next;

        }

​

        if (node1 == null || node2 == null)

        {

            return;

        }

​

        if (prev1 != null)

            prev1.Next = node2;

        else

            head = node2;

        if (prev2 != null)

            prev2.Next = node1;

        else

            head = node1;

        var temp = node1.Next;

        node1.Next = node2.Next;

        node2.Next = temp;

    }

}

​

public class Node

{

    public int Data

    {

        get;

        set;

    }

​

    public Node Next

    {

        get;

        set;

    }

​

    public Node(int data)

    {

        this.Data = data;

        this.Next = null;

    }

​

    public void Print()

    {

        var node = this;

        do

        {

            Console.WriteLine(node.Data);

            node = node.Next;

        }

        while (node != null);

    }

​

    public int GetLengthIterative()

    {

        var node = this;

        var count = 0;

        while (node != null)

        {

            count++;

            node = node.Next;

        }

​

        return count;

    }

​

    public int GetLengthRecursive()

    {

        if (this.Next == null)

        {

            return 1;

        }

​

        return 1 + this.Next.GetLengthRecursive();

    }

}