Python3 Program for Clockwise rotation of Linked List

# Python3 implementation of the approach

''' Link list node '''
class Node:

    def __init__(self, data):
        self.data = data
        self.next = None

''' A utility function to push a node '''
def push(head_ref, new_data):
  
    ''' allocate node '''
    new_node = Node(new_data)

    ''' put in the data '''
    new_node.data = new_data

    ''' link the old list off the new node '''
    new_node.next = (head_ref)

    ''' move the head to point to the new node '''
    (head_ref) = new_node

    return head_ref

''' A utility function to print linked list '''
def printList(node):
    while (node != None):
        print(node.data, end=' -> ')
        node = node.next
    print("NULL")

# Function that rotates the given linked list
# clockwise by k and returns the updated
# head pointer
def rightRotate(head, k):

    # If the linked list is empty
    if (not head):
        return head

    # len is used to store length of the linked list
    # tmp will point to the last node after this loop
    tmp = head
    len = 1

    while (tmp.next != None):
        tmp = tmp.next
        len += 1

    # If k is greater than the size
    # of the linked list
    if (k > len):
        k = k % len

    # Subtract from length to convert
    # it into left rotation
    k = len - k

    # If no rotation needed then
    # return the head node
    if (k == 0 or k == len):
        return head

    # current will either point to
    # kth or None after this loop
    current = head
    cnt = 1

    while (cnt < k and current != None):
        current = current.next
        cnt += 1

    # If current is None then k is equal to the
    # count of nodes in the list
    # Don't change the list in this case
    if (current == None):
        return head

    # current points to the kth node
    kthnode = current

    # Change next of last node to previous head
    tmp.next = head

    # Change head to (k+1)th node
    head = kthnode.next

    # Change next of kth node to None
    kthnode.next = None

    # Return the updated head pointer
    return head


# Driver code
if __name__ == '__main__':

    ''' The constructed linked list is: 
    1.2.3.4.5 '''
    head = None
    head = push(head, 5)
    head = push(head, 4)
    head = push(head, 3)
    head = push(head, 2)
    head = push(head, 1)
    k = 2

    # Rotate the linked list
    updated_head = rightRotate(head, k)

    # Print the rotated linked list
    printList(updated_head)
    
    # This code is contributed by rutvik_56

# Python Program for rotating a Linked List by k

from collections import deque

class Node:
    def __init__(self, data):
        self.data = data
        self.next = None


def build(head, val):
    if(head == None):
        head = Node(val)
    else:
        temp = head
        while(temp.next != None):
            temp = temp.next
        temp.next = Node(val)
    return head

def printList(node):
    while(node != None):
        print(node.data, end = "->")
        node = node.next
    print("NULL")
    
def rotate_clockwise(head, k):
    if(head == None):
        return None
    q = deque([])
    temp = head
    while(temp != None):
        q.append(temp)
        temp = temp.next
    
    k %= len(q)
    while(k != 0):
        q[-1].next = q[0]
        q.appendleft(q[-1])
        q.pop()
        q[-1].next = None
        k = k-1
    
    return q[0]

head = None
head = build(head, 1)
head = build(head, 2)
head = build(head, 3)
head = build(head, 4)
head = build(head, 5)
k = 2
r = rotate_clockwise(head, k)
printList(r)

# This code is contributed by Yash Agarwal(yashagarwal2852002)