HackerRank - Linked List - get Node Value

getNodeValue.cpp

/*
  Get Nth element from the end in a linked list of integers
  Number of elements in the list will always be greater than N.
  Node is defined as 
  struct Node
  {
     int data;
     struct Node *next;
  }
*/
int GetNode(Node *head,int positionFromTail)
{
   if(head == NULL || positionFromTail < 0)
       return NULL; 
   
   Node * runner = head; 
   Node * prevLast = NULL; 
   int count = 0; 
   while(runner!=NULL)
   {    
       if(count == positionFromTail)
           prevLast = head; 
       else if(count> positionFromTail)
           prevLast = prevLast->next; 
       
       runner = runner->next; 
       count ++; 
   }
    
   return prevLast->data;    
}