Pairwise swap elements of a linked list Python

PROGRAM TO SWAP ELEMENTS PAIRWISE OF A GIVEN LINKED LIST

# Node class 

class Node:

  

    # Constructor to initialize the node object

    def __init__(self, data):

        self.data = data

        self.next = None

  

class LinkedList:

  

    # Function to initialize head

    def __init__(self):

        self.head = None

  

    # Function to pairwise swap elements of a linked list

    def pairwiseSwap(self):

        temp = self.head

         

        # There are no nodes in linked list

        if temp is None:

            return 

          

        # Traverse furthur only if there are at least two

        # left

        while(temp is not None and temp.next is not None):

              

            # If both nodes are same,

            # no need to swap data

            if(temp.data == temp.next.data):

                  

                # Move temp by 2 to the next pair

                temp = temp.next.next

            else:

                  

                # Swap data of node with its next node's data

                temp.data, temp.next.data = temp.next.data, temp.data

                  

                # Move temp by 2 to the next pair

                temp = temp.next.next

         

    # Function to insert a new node at the beginning

    def push(self, new_data):

        new_node = Node(new_data)

        new_node.next = self.head

        self.head = new_node

  

    # Utility function to prit the linked LinkedList

    def printList(self):

        temp = self.head

        while(temp):

            print temp.data,

            temp = temp.next

  

  

# Driver program

llist = LinkedList()

llist.push(5)

llist.push(4)

llist.push(3)

llist.push(2)

llist.push(1)

  

print "Linked list before calling pairWiseSwap() "

llist.printList()

  

llist.pairwiseSwap()

  

print  "\nLinked 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/