Added Reverse a doubly linked list (Python) aditya109#283

Signed-off-by: Nazish Khan <nazish1771@gmail.com>

Programming/Python/ReverseDoublyLinkedList/ReverseDoublyLinkedList.py

@@ -0,0 +1,72 @@
+#!/bin/python3
+
+# Program to inplement reversal of a Doubly LinkedList.
+
+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):
+ while node:
+ print(str(node.data), end=' ')
+ node = node.next
+
+
+# DoublyLinkedListNode:
+# int data
+# DoublyLinkedListNode next
+# DoublyLinkedListNode prev
+
+def reverse(head):
+ r = head
+ p = None
+ while r!=None:
+ q = r.next
+ r.next = p
+ r.prev = q
+ p = r
+ r = q
+ return p
+
+
+if __name__ == '__main__':
+ t = int(input())
+
+ for t_itr in range(t):
+ llist_count = int(input())
+
+ llist = DoublyLinkedList()
+
+ for _ in range(llist_count):
+ llist_item = int(input())
+ llist.insert_node(llist_item)
+
+ llist1 = reverse(llist.head)
+
+ print_doubly_linked_list(llist1, ' ')
+