# Rotate Linked List block wise

• Difficulty Level : Medium
• Last Updated : 15 Jun, 2022

Given a Linked List of length n and block length k rotate in a circular manner towards right/left each block by a number d. If d is positive rotate towards right else rotate towards left.

Examples:

```Input: 1->2->3->4->5->6->7->8->9->NULL,
k = 3
d = 1
Output: 3->1->2->6->4->5->9->7->8->NULL
Explanation: Here blocks of size 3 are
rotated towards right(as d is positive)
by 1.

Input: 1->2->3->4->5->6->7->8->9->10->
11->12->13->14->15->NULL,
k = 4
d = -1
Output: 2->3->4->1->6->7->8->5->10->11
->12->9->14->15->13->NULL
Explanation: Here, at the end of linked
list, remaining nodes are less than k, i.e.
only three nodes are left while k is 4.
Rotate those 3 nodes also by d.```

The idea is if the absolute value of d is greater than the value of k, then rotate the link list by d % k times. If d is 0, no need to rotate the linked list at all.

## C++

 `// C++ program to rotate a linked list block wise``#include``using` `namespace` `std;` `/* Link list node */``class` `Node``{``    ``public``:``    ``int` `data;``    ``Node* next;``};` `// Recursive function to rotate one block``Node* rotateHelper(Node* blockHead,``                        ``Node* blockTail,``                        ``int` `d, Node** tail,``                        ``int` `k)``{``    ``if` `(d == 0)``        ``return` `blockHead;` `    ``// Rotate Clockwise``    ``if` `(d > 0)``    ``{``        ``Node* temp = blockHead;``        ``for` `(``int` `i = 1; temp->next->next &&``                        ``i < k - 1; i++)``            ``temp = temp->next;``        ``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``Node* rotateByBlocks(Node* head,``                                ``int` `k, ``int` `d)``{``    ``// If length is 0 or 1 return head``    ``if` `(!head || !head->next)``        ``return` `head;` `    ``// if degree of rotation is 0, return head``    ``if` `(d == 0)``        ``return` `head;` `    ``Node* temp = head, *tail = NULL;` `    ``// Traverse upto last element of this block``    ``int` `i;``    ``for` `(i = 1; temp->next && i < k; i++)``        ``temp = temp->next;` `    ``// storing the first node of next block``    ``Node* nextBlock = temp->next;` `    ``// If nodes of this block are less than k.``    ``// Rotate this block also``    ``if` `(i < k)``        ``head = rotateHelper(head, temp, d % k,``                                    ``&tail, i);``    ``else``        ``head = 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 */``void` `push(Node** head_ref, ``int` `new_data)``{``    ``Node* new_node = ``new` `Node;``    ``new_node->data = new_data;``    ``new_node->next = (*head_ref);``    ``(*head_ref) = new_node;``}` `/* Function to print linked list */``void` `printList(Node* node)``{``    ``while` `(node != NULL)``    ``{``        ``cout << node->data << ``" "``;``        ``node = node->next;``    ``}``}` `/* Driver code*/``int` `main()``{``    ``/* Start with the empty list */``    ``Node* head = NULL;` `    ``// create a list 1->2->3->4->5->``    ``// 6->7->8->9->NULL``    ``for` `(``int` `i = 9; i > 0; i -= 1)``        ``push(&head, i);` `    ``cout<<``"Given linked list \n"``;``    ``printList(head);` `    ``// k is block size and d is number of``    ``// rotations in every block.``    ``int` `k = 3, d = 2;``    ``head = rotateByBlocks(head, k, d);` `    ``cout << ``"\nRotated by blocks Linked list \n"``;``    ``printList(head);` `    ``return` `(0);``}` `// This is code is contributed by rathbhupendra`

## C

 `// C program to rotate a linked list block wise``#include ``#include ` `/* Link list node */``struct` `Node {``    ``int` `data;``    ``struct` `Node* next;``};` `// Recursive function to rotate one block``struct` `Node* rotateHelper(``struct` `Node* blockHead,``                          ``struct` `Node* blockTail,``                          ``int` `d, ``struct` `Node** tail,``                          ``int` `k)``{``    ``if` `(d == 0)``        ``return` `blockHead;` `    ``// Rotate Clockwise``    ``if` `(d > 0) {``        ``struct` `Node* temp = blockHead;``        ``for` `(``int` `i = 1; temp->next->next &&``                        ``i < k - 1; i++)``            ``temp = temp->next;``        ``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``struct` `Node* rotateByBlocks(``struct` `Node* head,``                                 ``int` `k, ``int` `d)``{``    ``// If length is 0 or 1 return head``    ``if` `(!head || !head->next)``        ``return` `head;` `    ``// if degree of rotation is 0, return head``    ``if` `(d == 0)``        ``return` `head;` `    ``struct` `Node* temp = head, *tail = NULL;` `    ``// Traverse upto last element of this block``    ``int` `i;``    ``for` `(i = 1; temp->next && i < k; i++)``        ``temp = temp->next;` `    ``// storing the first node of next block``    ``struct` `Node* nextBlock = temp->next;` `    ``// If nodes of this block are less than k.``    ``// Rotate this block also``    ``if` `(i < k)``        ``head = rotateHelper(head, temp, d % k,``                                    ``&tail, i);``    ``else``        ``head = 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 */``void` `push(``struct` `Node** head_ref, ``int` `new_data)``{``    ``struct` `Node* new_node = ``new` `Node;``    ``new_node->data = new_data;``    ``new_node->next = (*head_ref);``    ``(*head_ref) = new_node;``}` `/* Function to print linked list */``void` `printList(``struct` `Node* node)``{``    ``while` `(node != NULL) {``        ``printf``(``"%d "``, node->data);``        ``node = node->next;``    ``}``}` `/* Driver program to test above function*/``int` `main()``{``    ``/* Start with the empty list */``    ``struct` `Node* head = NULL;` `    ``// create a list 1->2->3->4->5->``    ``// 6->7->8->9->NULL``    ``for` `(``int` `i = 9; i > 0; i -= 1)``        ``push(&head, i);` `    ``printf``(``"Given linked list \n"``);``    ``printList(head);` `    ``// k is block size and d is number of``    ``// rotations in every block.``    ``int` `k = 3, d = 2;``    ``head = rotateByBlocks(head, k, d);` `    ``printf``(``"\nRotated by blocks Linked list \n"``);``    ``printList(head);` `    ``return` `(0);``}`

## Java

 `// Java program to rotate a linked list block wise``import` `java.util.*;``class` `GFG``{` `/* Link list node */``static` `class` `Node``{``    ``int` `data;``    ``Node next;``};``static` `Node tail;``  ` `// Recursive function to rotate one block``static` `Node rotateHelper(Node blockHead,``                        ``Node blockTail,``                        ``int` `d,``                        ``int` `k)``{``    ``if` `(d == ``0``)``        ``return` `blockHead;` `    ``// Rotate Clockwise``    ``if` `(d > ``0``)``    ``{``        ``Node temp = blockHead;``        ``for` `(``int` `i = ``1``; temp.next.next!=``null` `&&``                        ``i < k - ``1``; i++)``            ``temp = temp.next;``        ``blockTail.next = blockHead;``        ``tail = temp;``        ``return` `rotateHelper(blockTail, temp,``                            ``d - ``1``,  k);``    ``}` `    ``// Rotate anti-Clockwise``    ``if` `(d < ``0``)``    ``{``        ``blockTail.next = blockHead;``        ``tail = blockHead;``        ``return` `rotateHelper(blockHead.next,``                ``blockHead, d + ``1``,  k);``    ``}``    ``return` `blockHead;``}` `// Function to rotate the linked list block wise``static` `Node rotateByBlocks(Node head,``                                ``int` `k, ``int` `d)``{``    ``// If length is 0 or 1 return head``    ``if` `(head == ``null` `|| head.next == ``null``)``        ``return` `head;` `    ``// if degree of rotation is 0, return head``    ``if` `(d == ``0``)``        ``return` `head;` `    ``Node temp = head;``    ``tail = ``null``;` `    ``// Traverse upto last element of this block``    ``int` `i;``    ``for` `(i = ``1``; temp.next != ``null` `&& i < k; i++)``        ``temp = temp.next;` `    ``// storing the first node of next block``    ``Node nextBlock = temp.next;` `    ``// If nodes of this block are less than k.``    ``// Rotate this block also``    ``if` `(i < k)``        ``head = rotateHelper(head, temp, d % k,``                                   ``i);``    ``else``        ``head = rotateHelper(head, temp, d % k,``                                    ``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 */``static` `Node push(Node head_ref, ``int` `new_data)``{``    ``Node new_node = ``new` `Node();``    ``new_node.data = new_data;``    ``new_node.next = head_ref;``    ``head_ref = new_node;``    ``return` `head_ref;``    ` `}` `/* Function to print linked list */``static` `void` `printList(Node node)``{``    ``while` `(node != ``null``)``    ``{``        ``System.out.print(node.data + ``" "``);``        ``node = node.next;``    ``}``}` `/* Driver code*/``public` `static` `void` `main(String[] args)``{``  ` `    ``/* Start with the empty list */``    ``Node head = ``null``;` `    ``// create a list 1.2.3.4.5.``    ``// 6.7.8.9.null``    ``for` `(``int` `i = ``9``; i > ``0``; i -= ``1``)``        ``head = push(head, i);``    ``System.out.print(``"Given linked list \n"``);``    ``printList(head);` `    ``// k is block size and d is number of``    ``// rotations in every block.``    ``int` `k = ``3``, d = ``2``;``    ``head = rotateByBlocks(head, k, d);``    ``System.out.print(``"\nRotated by blocks Linked list \n"``);``    ``printList(head);``}``}` `// This code contributed by aashish1995`

## Python3

 `# 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``(``"\nRotated by blocks Linked list "``)``    ``printList(head)`` ` `# This code is contributed by rutvik_56`

## C#

 `// C# program to rotate a linked list block wise``using` `System;``public` `class` `GFG``{` `  ``/* Link list node */``  ``public``    ``class` `Node``    ``{``      ``public``        ``int` `data;``      ``public``        ``Node next;``    ``};``  ``static` `Node tail;` `  ``// Recursive function to rotate one block``  ``static` `Node rotateHelper(Node blockHead,``                           ``Node blockTail,``                           ``int` `d,``                           ``int` `k)``  ``{``    ``if` `(d == 0)``      ``return` `blockHead;` `    ``// Rotate Clockwise``    ``if` `(d > 0)``    ``{``      ``Node temp = blockHead;``      ``for` `(``int` `i = 1; temp.next.next != ``null` `&&``           ``i < k - 1; i++)``        ``temp = temp.next;``      ``blockTail.next = blockHead;``      ``tail = temp;``      ``return` `rotateHelper(blockTail, temp,``                          ``d - 1, k);``    ``}` `    ``// Rotate anti-Clockwise``    ``if` `(d < 0)``    ``{``      ``blockTail.next = blockHead;``      ``tail = blockHead;``      ``return` `rotateHelper(blockHead.next,``                          ``blockHead, d + 1,  k);``    ``}``    ``return` `blockHead;``  ``}` `  ``// Function to rotate the linked list block wise``  ``static` `Node rotateByBlocks(Node head,``                             ``int` `k, ``int` `d)``  ``{``    ``// If length is 0 or 1 return head``    ``if` `(head == ``null` `|| head.next == ``null``)``      ``return` `head;` `    ``// if degree of rotation is 0, return head``    ``if` `(d == 0)``      ``return` `head;``    ``Node temp = head;``    ``tail = ``null``;` `    ``// Traverse upto last element of this block``    ``int` `i;``    ``for` `(i = 1; temp.next != ``null` `&& i < k; i++)``      ``temp = temp.next;` `    ``// storing the first node of next block``    ``Node nextBlock = temp.next;` `    ``// If nodes of this block are less than k.``    ``// Rotate this block also``    ``if` `(i < k)``      ``head = rotateHelper(head, temp, d % k,``                          ``i);``    ``else``      ``head = rotateHelper(head, temp, d % k,``                          ``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 */``  ``static` `Node push(Node head_ref, ``int` `new_data)``  ``{``    ``Node new_node = ``new` `Node();``    ``new_node.data = new_data;``    ``new_node.next = head_ref;``    ``head_ref = new_node;``    ``return` `head_ref;` `  ``}` `  ``/* Function to print linked list */``  ``static` `void` `printList(Node node)``  ``{``    ``while` `(node != ``null``)``    ``{``      ``Console.Write(node.data + ``" "``);``      ``node = node.next;``    ``}``  ``}` `  ``/* Driver code*/``  ``public` `static` `void` `Main(String[] args)``  ``{` `    ``/* Start with the empty list */``    ``Node head = ``null``;` `    ``// create a list 1.2.3.4.5.``    ``// 6.7.8.9.null``    ``for` `(``int` `i = 9; i > 0; i -= 1)``      ``head = push(head, i);``    ``Console.Write(``"Given linked list \n"``);``    ``printList(head);` `    ``// k is block size and d is number of``    ``// rotations in every block.``    ``int` `k = 3, d = 2;``    ``head = rotateByBlocks(head, k, d);``    ``Console.Write(``"\nRotated by blocks Linked list \n"``);``    ``printList(head);``  ``}``}` `// This code is contributed by aashish1995`

## Javascript

 ``

Output:

```Given linked list
1 2 3 4 5 6 7 8 9
2 3 1 5 6 4 8 9 7```

Time complexity: O(n) since using a single loop to traverse a linked list to rotate

Auxiliary Space: O(n) for call stack

This article is contributed by Chhavi. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.