Pairwise swap elements of a linked list Java

PROGRAM TO SWAP ELEMENTS PAIRWISE OF A GIVEN LINKED LIST

class LinkedList {

    Node head; // head of list

  

    /* Linked list Node*/

    class Node {

        int data;

        Node next;

        Node(int d)

        {

            data = d;

            next = null;

        }

    }

  

    void pairWiseSwap()

    {

        Node temp = head;

  

        /* Traverse only till there are atleast 2 nodes left */

        while (temp != null && temp.next != null) {

  

            /* Swap the data */

            int k = temp.data;

            temp.data = temp.next.data;

            temp.next.data = k;

            temp = temp.next.next;

        }

    }

  

    /* Utility functions */

  

    /* Inserts a new Node at front of the list. */

    public void push(int new_data)

    {

        /* 1 & 2: Allocate the Node &

                  Put in the data*/

        Node new_node = new Node(new_data);

  

        /* 3. Make next of new Node as head */

        new_node.next = head;

  

        /* 4. Move the head to point to new Node */

        head = new_node;

    }

  

    /* Function to print linked list */

    void printList()

    {

        Node temp = head;

        while (temp != null) {

            System.out.print(temp.data + " ");

            temp = temp.next;

        }

        System.out.println();

    }

  

    /* Driver program to test above functions */

    public static void main(String args[])

    {

        LinkedList llist = new LinkedList();

  

        /* Created Linked List 1->2->3->4->5 */

        llist.push(5);

        llist.push(4);

        llist.push(3);

        llist.push(2);

        llist.push(1);

  

        System.out.println("Linked List before calling pairWiseSwap() ");

        llist.printList();

  

        llist.pairWiseSwap();

  

        System.out.println("Linked List after calling pairWiseSwap() ");

        llist.printList();

    }

}




OUTPUT

Linked List before calling pairWiseSwap() 
1 2 3 4 5 
Linked List after calling pairWiseSwap() 
2 1 4 3 5 

CREDITS: https://www.geeksforgeeks.org/pairwise-swap-elements-of-a-given-linked-list/