HackerRank - LinkedList - Merge Two sorted Linked List

mergeTwoSortedLinkedList.cpp

/*
  Merge two sorted lists A and B as one linked list
  Node is defined as 
  struct Node
  {
     int data;
     struct Node *next;
  }
*/
Node* MergeLists(Node *headA, Node* headB)
{
  if(headA == NULL && headB == NULL)
      return NULL;
  if(headA == NULL)
      return headB; 
  if(headB == NULL)
      return headA; 
  if(headA->data <= headB->data)
  {
      headA->next = MergeLists(headA->next, headB); 
      return headA;       
  }
  else 
  {
      headB->next = MergeLists(headA, headB->next);     
      return headB; 
  }   
}