Python3 Program To Rotate Linked List Block Wise

# Python3 program to rotate a linked
# list block wise 

# Link list node 
class Node:    
    def __init__(self, data):      
        self.data = data
        self.next = None

# Recursive function to rotate one block 
def rotateHelper(blockHead, blockTail,
                 d, tail, k):    
    if (d == 0):
        return blockHead, tail 
 
    # Rotate Clockwise 
    if (d > 0):
        temp = blockHead 
        i = 1        
        while (temp.next.next != None and 
               i < k - 1):
            temp = temp.next
            i += 1            
        blockTail.next = blockHead
        tail = temp
        return rotateHelper(blockTail, temp, 
                            d - 1, tail, k)

    # Rotate anti-Clockwise 
    if (d < 0):
        blockTail.next = blockHead 
        tail = blockHead
        return rotateHelper(blockHead.next, 
                            blockHead, d + 1, 
                            tail, k) 
    
# Function to rotate the linked list 
# block-wise 
def rotateByBlocks(head, k, d):

    # If length is 0 or 1 return head 
    if (head == None or head.next == None):
        return head
 
    # If degree of rotation is 0, return head 
    if (d == 0):
        return head 
    temp = head
    tail = None
 
    # Traverse upto last element of this block 
    i = 1    
    while temp.next != None and i < k:
        temp = temp.next 
        i += 1
 
    # Storing the first node of next block 
    nextBlock = temp.next
 
    # If nodes of this block are less than k. 
    # Rotate this block also 
    if (i < k):
        head, tail = rotateHelper(head, temp, 
                                  d % k, tail, i) 
    else:
        head, tail = rotateHelper(head, temp, 
                                  d % k, tail, k) 
 
    # Append the new head of next block to 
    # the tail of this block 
    tail.next = rotateByBlocks(nextBlock, 
                               k, d % k);
 
    # Return head of updated Linked List 
    return head; 

# UTILITY FUNCTIONS 
# Function to push a node 
def push(head_ref, new_data):

    new_node = Node(new_data)
    new_node.data = new_data 
    new_node.next = (head_ref) 
    (head_ref) = new_node
    return head_ref

# Function to print linked list 
def printList(node):
    while (node != None):
        print(node.data, end = ' ')
        node = node.next 
    
# Driver code
if __name__=='__main__':
    
    # Start with the empty list
    head = None
 
    # Create a list 1.2.3.4.5. 
    # 6.7.8.9.None 
    for  i in range(9, 0, -1):
        head = push(head, i) 
    print("Given linked list ")
    printList(head)
 
    # k is block size and d is number 
    # of rotations in every block. 
    k = 3
    d = 2
    head = rotateByBlocks(head, k, d)
 
    print(
    "Rotated by blocks Linked list ")
    printList(head)
 # This code is contributed by rutvik_56