singly linked list swap kth node with kth from end - I want to celebrate the success of training after a few hours. Exhausted!

SinglyLinkedListSwapKthNodeWithKthFromEnd.cs

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

namespace SwapKthAndKthToLastNodeValues
{
    class Node
    {
        public int Value { get; set; }
        public Node Next { get; set; }

        public Node(int val)
        {
            Value = val;
        }
    }

    /// <summary>
    /// May 15, 2018
    /// swap a singly linked list kth node with kth to last node. 
    /// </summary>
    class Program
    {
        static void Main(string[] args)
        {
            RunTestcase();
        }

        public static void RunTestcase()
        {
            var root = new Node(1);
            root.Next = new Node(2);
            root.Next.Next = new Node(3);
            root.Next.Next.Next = new Node(4);
            root.Next.Next.Next.Next = new Node(5);
            root.Next.Next.Next.Next.Next = new Node(6);

            var afterSwap = ReverseKthAndKthToLastInSingleLinkedList(root, 2);
        }

        /// <summary>
        /// May 15, 2018
        /// reverse kth node and kth to last node in a singly linked list
        /// </summary>
        /// <param name="root"></param>
        /// <param name="k"></param>
        /// <returns></returns>
        public static Node ReverseKthAndKthToLastInSingleLinkedList(Node root, int k)
        {
            if (root == null || k <= 0)
            {
                return null;
            }

            var length = getLength(root);
            if (k > length)
            {
                return root;
            }

            var kthNode = getKthNode(root, k);
            var kthToLastNode = getKthFromEnd(root, k, length);

            // swap two nodes' values instead of changing the point 
            var tmp = kthNode.Value;
            kthNode.Value = kthToLastNode.Value;
            kthToLastNode.Value = tmp;

            return root;
        }

        /// <summary>
        /// I had a headache since I got up too early. 
        /// </summary>
        /// <param name="root"></param>
        /// <returns></returns>
        public static int getLength(Node root)
        {
            if (root == null)
            {
                return 0;
            }

            return 1 + getLength(root.Next); 
        }

        /// <summary>
        /// kth node - how to define?
        /// </summary>
        /// <param name="root"></param>
        /// <param name="k"></param>
        /// <returns></returns>
        private static Node getKthNode(Node root, int k)
        {
            if (root == null || k <= 1)
            {
                return root; 
            }

            return getKthNode(root.Next, k - 1);
        }

        private static Node getKthFromEnd(Node root, int k, int length)
        {
            if (length == k)
            {
                return root; 
            }

            return getKthFromEnd(root.Next, k, length - 1);
        }
    }
}