Linked Lists-Reverse a doubly linked list.py

#Problem Link : https://www.hackerrank.com/challenges/reverse-a-doubly-linked-list/problem?isFullScreen=true&h_l=interview&playlist_slugs%5B%5D=interview-preparation-kit&playlist_slugs%5B%5D=linked-lists

#Ans:

#!/bin/python3

import math
import os
import random
import re
import sys

class DoublyLinkedListNode:
    def __init__(self, node_data):
        self.data = node_data
        self.next = None
        self.prev = None

class DoublyLinkedList:
    def __init__(self):
        self.head = None
        self.tail = None

    def insert_node(self, node_data):
        node = DoublyLinkedListNode(node_data)

        if not self.head:
            self.head = node
        else:
            self.tail.next = node
            node.prev = self.tail


        self.tail = node

def print_doubly_linked_list(node, sep, fptr):
    while node:
        fptr.write(str(node.data))

        node = node.next

        if node:
            fptr.write(sep)

#
# Complete the 'reverse' function below.
#
# The function is expected to return an INTEGER_DOUBLY_LINKED_LIST.
# The function accepts INTEGER_DOUBLY_LINKED_LIST llist as parameter.
#

#
# For your reference:
#
# DoublyLinkedListNode:
#     int data
#     DoublyLinkedListNode next
#     DoublyLinkedListNode prev
#
#


class DoublyLinkedListNode:
    def __init__(self, node_data):
        self.data = node_data
        self.next = None
        self.prev = None


class DoublyLinkedList:
    def __init__(self):
        self.head = None
        self.tail = None

    def insert_node(self, node_data):
        node = DoublyLinkedListNode(node_data)

        if not self.head:
            self.head = node
        else:
            self.tail.next = node
            node.prev = self.tail

        self.tail = node


def print_doubly_linked_list(node, sep, fptr):
    while node:
        fptr.write(str(node.data))

        node = node.next

        if node:
            fptr.write(sep)


# Complete the reverse function below.

#
# For your reference:
#
# DoublyLinkedListNode:
#     int data
#     DoublyLinkedListNode next
#     DoublyLinkedListNode prev
#
#
def reverse(head):
    result = head

    while head is not None:
        head.prev, head.next = head.next, head.prev
        result = head
        head = head.prev

    return result


if __name__ == '__main__':