Python3 Program to Rotate Doubly linked list by N nodes

# Node of a doubly linked list 
class Node: 
    def __init__(self, next = None, 
                       prev = None, data = None): 
        self.next = next # reference to next node in DLL 
        self.prev = prev # reference to previous node in DLL 
        self.data = data 

def push(head, new_data): 

    new_node = Node(data = new_data) 

    new_node.next = head 
    new_node.prev = None

    if head is not None: 
        head.prev = new_node 

    head = new_node
    return head

def printList(head):

    node = head

    print("Given linked list")
    while(node is not None): 
        print(node.data, end = " "), 
        last = node 
        node = node.next
    
def rotate(start, N):
    if N == 0 :
        return

    # Let us understand the below code 
    # for example N = 2 and 
    # list = a <-> b <-> c <-> d <-> e. 
    current = start 

    # current will either point to Nth 
    # or None after this loop. Current 
    # will point to node 'b' in the 
    # above example 
    count = 1
    while count < N and current != None :
        current = current.next
        count += 1

    # If current is None, N is greater 
    # than or equal to count of nodes 
    # in linked list. Don't change the 
    # list in this case 
    if current == None :
        return

    # current points to Nth node. Store 
    # it in a variable. NthNode points to 
    # node 'b' in the above example 
    NthNode = current 

    # current will point to last node 
    # after this loop current will point 
    # to node 'e' in the above example 
    while current.next != None :
        current = current.next

    # Change next of last node to previous 
    # head. Next of 'e' is now changed to 
    # node 'a' 
    current.next = start 

    # Change prev of Head node to current 
    # Prev of 'a' is now changed to node 'e' 
    start.prev = current 

    # Change head to (N+1)th node 
    # head is now changed to node 'c' 
    start = NthNode.next

    # Change prev of New Head node to None 
    # Because Prev of Head Node in Doubly 
    # linked list is None 
    start.prev = None

    # change next of Nth node to None 
    # next of 'b' is now None 
    NthNode.next = None

    return start

# Driver Code
if __name__ == "__main__":
    head = None

    head = push(head, 'e')
    head = push(head, 'd')
    head = push(head, 'c')
    head = push(head, 'b')
    head = push(head, 'a')

    printList(head)
    print("
")
    
    N = 2
    head = rotate(head, N)

    printList(head)

# This code is contributed by vinayak sharma