refactor: RotateListRight.js and added tests

Data-Structures/Linked-List/RotateListRight.js

@@ -2,21 +2,13 @@
  * A LinkedList based solution for Rotating a List to the right by k places
  */
 
-function main () {
+function rotateListRight (head, k) {
  /*
  Problem Statement:
  Given a linked list, rotate the list to the right by k places, where k is non-negative.
 
- Note:
- * While Solving the problem in given link below, don't use main() function.
- * Just use only the code inside main() function.
- * The purpose of using main() function here is to avoid global variables.
-
  Link for the Problem: https://leetcode.com/problems/rotate-list/
  */
- // Reference to both head and k is given in the problem. So please ignore below two lines
- let head = ''
- let k = ''
  let i = 0
  let current = head
  while (current) {
@@ -42,4 +34,4 @@ function main () {
  return head
 }
 
-main()
+export { rotateListRight }

Data-Structures/Linked-List/test/RotateListRight.test.js

@@ -0,0 +1,33 @@
+import { rotateListRight } from '../RotateListRight'
+import { Node } from '../SinglyLinkedList'
+
+describe('Rotate list by k steps', () => {
+ it('should shift every node by k steps towards right, shifts few tail nodes towards the start and change head of the list', () => {
+ // Case 0: when head is null
+ let headNode = rotateListRight(null, 0)
+ expect(headNode).toEqual(null)
+
+ // Creating list
+ headNode = new Node(10)
+ headNode.next = new Node(20)
+ headNode.next.next = new Node(30)
+ headNode.next.next.next = new Node(40)
+ headNode.next.next.next.next = new Node(50)
+
+ // Case 1: when k = 0 => List should be unaffected
+ headNode = rotateListRight(headNode, 0)
+ expect([headNode.data, headNode.next.data, headNode.next.next.data, headNode.next.next.next.data, headNode.next.next.next.next.data]).toEqual([10, 20, 30, 40, 50])
+
+ // Case 2: Rotate right by 2 steps
+ headNode = rotateListRight(headNode, 2)
+ expect([headNode.data, headNode.next.data, headNode.next.next.data, headNode.next.next.next.data, headNode.next.next.next.next.data]).toEqual([40, 50, 10, 20, 30])
+
+ // Case 3: Rotate right by 12 steps
+ headNode = rotateListRight(headNode, 12)
+ expect([headNode.data, headNode.next.data, headNode.next.next.data, headNode.next.next.next.data, headNode.next.next.next.next.data]).toEqual([20, 30, 40, 50, 10])
+
+ // Case 4: when k = length of the list = 5 => List should be unaffected
+ headNode = rotateListRight(headNode, 5)
+ expect([headNode.data, headNode.next.data, headNode.next.next.data, headNode.next.next.next.data, headNode.next.next.next.next.data]).toEqual([20, 30, 40, 50, 10])
+ })
+})