递归实现合并两个有序链表

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