void MergeList(LinkList &La, LinkList &Lb, LinkList &Lc)
{//有序链表的合并
	pa = La->next;	//pa和pb分别是链表La和Lb的工作指针,
	pb = Lb->next;	//分别初始化为相应链表的第一个结点
	Lc = pc = La;  //用La的头结点作为Lc的头结点
	while (pa && pb)
	{
		if (pa->data < pb->data)
		{
			pc->next = pa;//将pa链接在pc后
			pc = pa;
			pa = pa->next;//pa指针后移
		}
		else if (pa->data > pb->data)
		{//若Lb较小
			pc->next = pb;//将pb链接在pc后
			pc = pb;
			pb = pb->next;//pb指针后移
		}
		else 
		{//若La==Lb
			pc->next = pa;
			pc = pa;
			pa = pa->next;

			q = pb->next;//接下来三行为删除Lb
			delete pb;
			pb = q;
		}
	}
	pc->next = pa ? pa : pb;    //插入剩余段
	delete Lb;            //释放Lb的头结点
}