//自顶向下伸展树的插入
SplayTree Insert(ElementType Item, SplayTree T)
{
    static Position NewNode = NULL;

    if(NewNode == NULL)
    {
        NewNode = malloc(sizeof(struct SplayNode);
        if(NewNode == NULL)
            FatalError("Out of space!!!");
    }
    NewNode->Element = Item;

    if(T == NullNode)
    {
        NewNode->Left = NewNode->Right = NullNode;
        T = NewNode;
    }
    else
    {
        T = Splay(Item, T);
        if(Item < T->Element)
        {
            NewNode->Left = T->Left;
            NewNode->Right = T;
            T->Left = NullNode;
            T = NewNode;
        }
        else if(Item > T->Element)
        {
            NewNode->Right = T->Right;
            NewNode->Left = T;
            T->Right = NullNode;
            T = NewNode;
        }
        else return T;
    }

    NewNode = NULL; /*So next insert will call malloc;*/
    return T;
}

//自顶向下的删除过程
SplayTree Remove(ElementType Item, SplayTree T)
{
    Position NewTree;

    if(T != NullNode)
    {
        T = Splay(Item, T);
        if(Item == T->Element)
        {
            if(T->Left == NullNode)
                NewTree = T->Right;
            else
            {
                NewTree = T->Left;
                NewTree = Splay(Item, NewTree);
                NewTree->Right = T->Right;
            }
            free(T);
            T = NewTree;
        }
    }

    return T;
}