Rotate a Linked List by K values

PROBLEM :

Given a singly linked list, rotate the linked list counter-clockwise by k nodes. Where k is a given positive integer smaller than or equal to lenght of the linked list. For example, if the given linked list is 10->20->30->40->50->60 and k is 4, the list should be modified to 50->60->10->20->30->40.

Note: Function may assume that k is smaller than the count of nodes in linked list.

Input:

In this problem, complete the method which takes two argument: the head of the linked list and int k. We should not read any input from stdin/console.
The struct Node has a data part which stores the data and a next pointer which points to the next element of the linked list.
There are multiple test cases. For each test case, this method will be called individually.

Output:
Rotate the link list from index k and return its new head pointer.


Note: If you use "Test" or "Expected Output Button" use below example format

Example:
Input:
1
8
1 2 3 4 5 6 7 8
4

Output:
5 6 7 8 1 2 3 4

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SIMPLE c++ IMPLEMENTATION :
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/*
  Rotate a linked list after node k
  The input list will have at least one element
  Return pointer to head of rotated linked list
  Node is defined as
  struct node
  {
     int data;
     struct node *next;
  }
*/
void rotate(struct node **head_ref, int k)
{
    if((*head_ref)==NULL||k==0)
        return ;
       
    struct node *temp,*ptr;
    temp=(*head_ref) ;
   
    while(k!=1&&temp!=NULL)
    {
        temp=temp->next ;
        k-- ;
    }
   
    if(temp==NULL)
    return ;
   
    ptr=(*head_ref) ;
    while(ptr->next!=NULL)
    ptr=ptr->next ;
   
    ptr->next=(*head_ref) ;
    (*head_ref)=temp->next ;
    temp->next=NULL ;
   
}


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