链表实现多项式相加和相乘

#include<iostream>
using namespace std;
class Polynominal;
class Term
{
public:
Term(int c, int e);
Term(int c, int e, Term* next);
Term* InsertAfter(int c, int e);
private:
int coef;
int exp;
Term* link;
friend ostream & operator<<(ostream &, const Term &);
friend class Polynominal;
};

Term::Term(int c, int e) :coef(c), exp(e)
{
link = 0;
}
Term::Term(int c, int e, Term* next) : coef(c), exp(e)
{
link = next;
}
Term* Term::InsertAfter(int c, int e)
{
link = new Term(c, e, link);
return link;
}
ostream &operator <<(ostream & out, const Term& val)
{
if (val.coef == 0)
return out;
out << val.coef;
switch (val.exp)
{
case 0:break;
case 1:out << "X"; break;
default:out << "X^" << val.exp; break;
}
return out;
}

class Polynominal
{
public:
Polynominal();
~Polynominal();
void Output(ostream& out)const;
void AddTerms(istream& in);
void PolyAdd(Polynominal& r);
void PolyMult(Polynominal& r);
private:
Term* theList;
friend ostream & operator <<(ostream &, const Polynominal &);
friend istream & operator >>(istream &, Polynominal &);
friend Polynominal& operator +(Polynominal &, Polynominal &);
friend Polynominal& operator *(Polynominal &, Polynominal &);
};
Polynominal::Polynominal()
{
theList = new Term(0, -1);
theList->link = theList;
}
Polynominal::~Polynominal()
{
Term* p = theList->link;
while (p != theList)
{
theList->link = p->link;
delete p;
p = theList->link;
}
delete theList;
}
void Polynominal::AddTerms(istream & in)
{
Term* q = theList;
int c, e;
for (;;)
{
cout << "Input a term(coef,exp):\n" << endl;
cin >> c >> e;
if (e < 0)
break;
q = q->InsertAfter(c, e);
}
}
void Polynominal::Output(ostream& out) const
{
int first = 1;
Term *p = theList->link;
cout << "The polynominal is:\n" << endl;
for (; p != theList; p = p->link)
{
if (!first && (p->coef > 0))
out << "+";
first = 0;
out << *p;
}
cout << "\n" << endl;
}
void Polynominal::PolyAdd(Polynominal& r)
{
Term* q, *q1 = theList, *p;
p = r.theList->link;
q = q1->link;
while (p->exp >= 0)
{
while (p->exp < q->exp)
{
q1 = q; q = q->link;
}
if (p->exp == q->exp)
{
q->coef = q->coef + p->coef;
if (q->coef == 0)
{
q1->link = q->link;
delete (q);
q = q1->link;
}
else
{
q1 = q; q = q->link;
}
}
else
q1 = q1->InsertAfter(p->coef, p->exp); p = p->link;
}
}
ostream& operator <<(ostream &out, const Polynominal &x)
{
x.Output(out);
return out;
}
istream& operator >>(istream &in, Polynominal &x)
{
x.AddTerms(in);
return in;
}
Polynominal& operator +(Polynominal &a, Polynominal &b)
{
a.PolyAdd(b);
return a;
}
void Polynominal::PolyMult(Polynominal &r)
{
Term* q, *q1=theList, *p,*mult;
p = r.theList->link;
q = q1->link;
Polynominal temp;
int c = 0, e = 0;
mult = temp.theList->link;
for (q = r.theList->link; p->exp >= 0; p = p->link)
{
for (; q->exp >= 0; q = q->link)
{
c = p->coef*q->coef;
e = p->exp*q->exp;
mult=mult->InsertAfter(c, e);
}
}
for (p = temp.theList->link,q=this->theList->link; p->exp >= 0; p = p->link)
{
if (q->exp >= 0)
{
q->coef = q->coef;
q->exp = p->exp;
q = q->link;
}
else
{
c = p->coef;
e = p->exp;
q->InsertAfter(c, e);
}
}
}
Polynominal& operator *(Polynominal &a, Polynominal &b)
{
a.PolyMult(b);
return a;
}

#include"polynominal.h"
void main()
{
Polynominal p, q;
cin >> p;
cout << p;
cin >> q;
cout << q;
q = q + p;
cout << q;
q = q*p;
cout << q;
system("pause");
}