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# Count rotations in sorted and rotated linked list

Given a linked list of n nodes which is first sorted, then rotated by k elements. Find the value of k.

The idea is to traverse singly linked list to check condition whether current node value is greater than value of next node. If the given condition is true, then break the loop. Otherwise increase the counter variable and increase the node by node->next. Below is the implementation of this approach.

Implementation:

## C++

 `// Program for count number of rotations in``// sorted linked list.``#include ``using` `namespace` `std;``/* Linked list node */``struct` `Node {``    ``int` `data;``    ``struct` `Node* next;``};` `// Function that count number of``// rotation in singly linked list.``int` `countRotation(``struct` `Node* head)``{``    ``// declare count variable and assign it 1.``    ``int` `count = 0;` `    ``// declare a min variable and assign to``    ``// data of head node.``    ``int` `min = head->data;` `    ``// check that while head not equal to NULL.``    ``while` `(head != NULL) {` `        ``// if min value is greater then head->data``        ``// then it breaks the while loop and``        ``// return the value of count.``        ``if` `(min > head->data)``            ``break``;` `        ``count++;` `        ``// head assign the next value of head.``        ``head = head->next;``    ``}``    ``return` `count;``}` `// Function to push element in linked list.``void` `push(``struct` `Node** head, ``int` `data)``{``    ``// Allocate dynamic memory for newNode.``    ``struct` `Node* newNode = ``new` `Node;` `    ``// Assign the data into newNode.``    ``newNode->data = data;` `    ``// newNode->next assign the address of``    ``// head node.``    ``newNode->next = (*head);` `    ``// newNode become the headNode.``    ``(*head) = newNode;``}` `// Display linked list.``void` `printList(``struct` `Node* node)``{``    ``while` `(node != NULL) {``        ``printf``(``"%d "``, node->data);``        ``node = node->next;``    ``}``}` `// Driver functions``int` `main()``{``    ``// Create a node and initialize with NULL``    ``struct` `Node* head = NULL;` `    ``// push() insert node in linked list.``    ``// 15 -> 18 -> 5 -> 8 -> 11 -> 12``    ``push(&head, 12);``    ``push(&head, 11);``    ``push(&head, 8);``    ``push(&head, 5);``    ``push(&head, 18);``    ``push(&head, 15);` `    ``printList(head);``    ``cout << endl;``    ``cout << ``"Linked list rotated elements: "``;` `    ``// Function call countRotation()``    ``cout << countRotation(head) << endl;` `    ``return` `0;``}`

## Java

 `// Program for count number of rotations in``// sorted linked list.``import` `java.util.*;` `class` `GFG``{``  ` `/* Linked list node */``static` `class` `Node {``    ``int` `data;``    ``Node next;``};` `// Function that count number of``// rotation in singly linked list.``static` `int` `countRotation(Node head)``{``  ` `    ``// declare count variable and assign it 1.``    ``int` `count = ``0``;` `    ``// declare a min variable and assign to``    ``// data of head node.``    ``int` `min = head.data;` `    ``// check that while head not equal to null.``    ``while` `(head != ``null``) {` `        ``// if min value is greater then head.data``        ``// then it breaks the while loop and``        ``// return the value of count.``        ``if` `(min > head.data)``            ``break``;` `        ``count++;` `        ``// head assign the next value of head.``        ``head = head.next;``    ``}``    ``return` `count;``}` `// Function to push element in linked list.``static` `Node push(Node head, ``int` `data)``{``    ``// Allocate dynamic memory for newNode.``    ``Node newNode = ``new` `Node();` `    ``// Assign the data into newNode.``    ``newNode.data = data;` `    ``// newNode.next assign the address of``    ``// head node.``    ``newNode.next = (head);` `    ``// newNode become the headNode.``    ``(head) = newNode;``    ``return` `head;``}` `// Display linked list.``static` `void` `printList(Node node)``{``    ``while` `(node != ``null``) {``        ``System.out.printf(``"%d "``, node.data);``        ``node = node.next;``    ``}``}` `// Driver functions``public` `static` `void` `main(String[] args)``{``  ` `    ``// Create a node and initialize with null``    ``Node head = ``null``;` `    ``// push() insert node in linked list.``    ``// 15.18.5.8.11.12``    ``head = push(head, ``12``);``    ``head = push(head, ``11``);``    ``head = push(head, ``8``);``    ``head = push(head, ``5``);``    ``head = push(head, ``18``);``    ``head = push(head, ``15``);` `    ``printList(head);``    ``System.out.println();``    ``System.out.print(``"Linked list rotated elements: "``);` `    ``// Function call countRotation()``    ``System.out.print(countRotation(head) +``"\n"``);` `}``}` `// This code contributed by gauravrajput1`

## Python3

 `# Program for count number of rotations in``# sorted linked list.` `# Linked list node``class` `Node:``    ` `    ``def` `__init__(``self``, data):``        ` `        ``self``.data ``=` `data``        ``self``.``next` `=` `None` `# Function that count number of``# rotation in singly linked list.``def` `countRotation(head):` `    ``# Declare count variable and assign it 1.``    ``count ``=` `0`` ` `    ``# Declare a min variable and assign to``    ``# data of head node.``    ``min` `=` `head.data`` ` `    ``# Check that while head not equal to None.``    ``while` `(head !``=` `None``):`` ` `        ``# If min value is greater then head->data``        ``# then it breaks the while loop and``        ``# return the value of count.``        ``if` `(``min` `> head.data):``            ``break`` ` `        ``count ``+``=` `1`` ` `        ``# head assign the next value of head.``        ``head ``=` `head.``next``    ` `    ``return` `count` `# Function to push element in linked list.``def` `push(head, data):` `    ``# Allocate dynamic memory for newNode.``    ``newNode ``=` `Node(data)`` ` `    ``# Assign the data into newNode.``    ``newNode.data ``=` `data`` ` `    ``# newNode->next assign the address of``    ``# head node.``    ``newNode.``next` `=` `(head)`` ` `    ``# newNode become the headNode.``    ``(head) ``=` `newNode``    ``return` `head` `# Display linked list.``def` `printList(node):` `    ``while` `(node !``=` `None``):``        ``print``(node.data, end ``=` `' '``)``        ``node ``=` `node.``next``    ` `# Driver code``if` `__name__``=``=``'__main__'``:``    ` `    ``# Create a node and initialize with None``    ``head ``=` `None`` ` `    ``# push() insert node in linked list.``    ``# 15 -> 18 -> 5 -> 8 -> 11 -> 12``    ``head ``=` `push(head, ``12``)``    ``head ``=` `push(head, ``11``)``    ``head ``=` `push(head, ``8``)``    ``head ``=` `push(head, ``5``)``    ``head ``=` `push(head, ``18``)``    ``head ``=` `push(head, ``15``)`` ` `    ``printList(head);``    ``print``()``    ``print``(``"Linked list rotated elements: "``,``          ``end ``=` `'')`` ` `    ``# Function call countRotation()``    ``print``(countRotation(head))` `# This code is contributed by rutvik_56`

## C#

 `// Program for count number of rotations in``// sorted linked list.``using` `System;``class` `LinkedList{``      ` `// Head of linked list ``Node head;``  ` `// Linked list node``class` `Node``{``    ``public` `int` `data;``    ``public` `Node next;``      ` `    ``public` `Node(``int` `d)``    ``{``        ``data = d;``        ``next = ``null``;``    ``}``}``  ` `int` `countRotation()``{``    ``// declare count variable and assign it 1.``    ``int` `count = 0;`` ` `    ``// declare a min variable and assign to``    ``// data of head node.``    ``int` `min = head.data;`` ` `    ``// check that while head not equal to NULL.``    ``while` `(head != ``null``) {`` ` `        ``// if min value is greater then head->data``        ``// then it breaks the while loop and``        ``// return the value of count.``        ``if` `(min > head.data)``            ``break``;`` ` `        ``count++;`` ` `        ``// head assign the next value of head.``        ``head = head.next;``    ``}``    ``return` `count;``}``  ` `// Inserts a new Node at front of the list.``public` `void` `push(``int` `new_data)``{``      ` `    ``/* 1 & 2: Allocate the Node &``              ``Put in the data*/``    ``Node new_node = ``new` `Node(new_data);``  ` `    ``/* 3. Make next of new Node as head */``    ``new_node.next = head;``  ` `    ``/* 4. Move the head to point to new Node */``    ``head = new_node;``}``  ` `// Function that count number of``// rotation in singly linked list.``public` `void` `printList()``{``    ``Node tnode = head;``    ``while` `(tnode != ``null``)``    ``{``        ``Console.Write(tnode.data + ``"->"``);``        ``tnode = tnode.next;``    ``}``    ``Console.WriteLine(``"NULL"``);``}``  ` `// Driver code``static` `public` `void` `Main()``{``    ``LinkedList llist = ``new` `LinkedList();``    ` `    ``llist.push(12);``    ``llist.push(11);``    ``llist.push(8);``    ``llist.push(5);``    ``llist.push(18);``    ``llist.push(15);``        ` `    ``llist.printList();``    ``Console.Write(``"Linked list rotated elements: "``);``    ``Console.WriteLine(llist.countRotation());``}``}``  ` `// This code is contributed by Aarti_Rathi`

## Javascript

 ``

Output

```15 18 5 8 11 12