Swap Kth nodes from ends

import java.util.*;
import java.lang.*;
import java.io.*;

public class Main
{

         // Node class
    static class Node{
       int data; Node next;
       Node(int val)
      {
          data = val;
          next = null;
      }
    }

    // function to create a LL
    static Node createLL(int len, int[] arr)
    {
         Node head = null, tail = null;
         for(int i = 0; i<len; i++)
           {
               Node newNode = new Node(arr[i]);
               if(head == null)
               {
                   head = newNode;
                   tail = newNode;
               }
               else
               {
                   tail.next = newNode;
                   tail = newNode;
               }
           }
       return head;
    }

    // count he number of nodes
    static int countNodes(Node head)
    {
        int cnt = 0;
        while(head != null)
          {
              cnt++;
              head = head.next;
          }
       return cnt;
    }

    // print the LL
    static void printLL(Node head)
    {
       while(head != null)
         {
             System.out.print(head.data+ " ");
             head = head.next;
         }
    }

      // Swap the kth nodes from start and end
        static Node swapKthNode(Node head, int n, int k)
        {
                //base cases
                if(head == null || head.next == null)
                        return head;

                // no swapping reqd
                if (k == n-k+1)
                        return head;
                else
                {
                        Node first = head, second = head;
                        Node first_prev = null, second_prev = null;

                        for(int i = 1; i<k; i++)
                        {
                                first_prev = first;
                                first = first.next;
                        }

                        for(int i = 1; i<n-k+1; i++)
                        {
                                  second_prev = second;
                                  second = second.next;
                        }

                        if(first_prev != null)
                                first_prev.next = second;

                        if(second_prev != null)
                                second_prev.next = first;

                        Node temp = first.next;
                        first.next = second.next;
                        second.next = temp;

                        if(k == 1)
                                head = second;

                        if(k == n)
                                head = first;

                }


                return head;
        }

    public static void main (String[] args) throws java.lang.Exception
    {
        //your code here
                Scanner sc = new Scanner(System.in);
                int n = sc.nextInt();
                int k = sc.nextInt();

                int arr[];
                 arr = new int[n];

                for(int i = 0; i<n; i++)
                        arr[i] = sc.nextInt();

                Node head = createLL(n, arr);

                head = swapKthNode(head, n, k);

                printLL(head);
    }
}