递归合并两个有序链表（包含非递归实现）

Node * MergeRecursive(Node *head1 , Node *head2)
{
   if ( head1 == NULL )
       return head2 ;
   if ( head2 == NULL)
       return head1 ;
   Node *head = NULL ;
   if ( head1->data < head2->data )
   {
       head = head1 ;
       head->next = MergeRecursive(head1->next,head2);
   }
   else
   {
       head = head2 ;
       head->next = MergeRecursive(head1,head2->next);
  }
   return head ;
}