链表实现稀疏多项式相加（C++）

#include
using namespace std;
typedef struct node
{
	float coef;//系数
	int expn;//指数
	struct node* next;
}list,*linklist;
void Createlist(linklist& l)
{
	l = new list;
	l->next = NULL;
	linklist p,q;
	q = l;
	cout << "输入多项式项数：" << endl;
	int n;
	cin >> n;
	for (int i = 0; i < n; i++)
	{
		p = new list;
		cout << "分别输入指数，系数:" << endl;
		cin >> p->expn >> p->coef;
		q->next = p;
		q = p;
	}
	q->next = NULL;
}
void Add(linklist& L1,linklist&L2)
{
	linklist p1, p2, p3,r;
	r = NULL;
	p1 = L1->next,p2=L2->next;
	p3 = L1;//新加多项式用L1表头
	while (p1 && p2)//两链表都不为空
	{
		if (p1->expn == p2->expn)//指数相等，进行运算
		{
			int sum = p1->coef + p2->coef;
			if (sum != 0)//系数和不为0
			{
				p1->coef = sum;//和存入链表一
				p3->next = p1;//新链表指向p1
				p3 = p1;
				p1 = p1->next;//p1往下走
				r = p2;
				p2 = p2->next;//p2往下走
				delete r;
			}
			else//和为0
			{
				r = p1; p1 = p1->next; delete r;//p1往下走
				r = p2; p2 = p2->next; delete r;//p2往下走
			}
		}
		else if(p1->expnexpn)//p1中的指数小于p2中的指数
		{
			p3->next = p1;//新链表指向p1
			p3 = p1;
			p1 = p1->next;
		}
		else//p2中的指数小于p1中的指数
		{
			p3->next = p2;//新链表指向p2
			p3 = p2;
			p2 = p2->next;
		}
	}
	p3->next = p1 ? p1 : p2;//p1不为空，接p1；p1为空，接p2
	delete L2;
}
void Printlist(linklist& l)
{
	linklist p;
	p = l->next;
	cout << "f = ";
	while (p)
	{
		if (p->expn == 0)
			cout << p->coef;
		else
		cout <<" + "<< p->coef << "x^" << p->expn;
		p = p->next;
	}
	cout << endl;
}
int main()
{
	linklist L1,L2;
	Createlist(L1);
	Createlist(L2);
	cout << "多项式一：" << endl;
	Printlist(L1);
	cout << "多项式二：" << endl;
	Printlist(L2);
	Add(L1, L2);
	cout << "多项式相加：" << endl;
	Printlist(L1);
}