基本上照著書打就可以了.......

#include <iostream>

using namespace std;

struct Term {
    float coef;
    int exp;
    Term *link;
    Term (float c, int e, Term *next = 0)
    {
        coef = c;
        exp = e;
        link = next;
    }
    Term* InsertAfter (float c, int e);
    friend ostream& operator<< (ostream&, const Term&);
};

class Polynomal {
public:
    Polynomal () {first = new Term(0, -1);}
    Polynomal (Polynomal &R);
    int maxOrder();
    Term* getHead() const {return first;}
private:
    Term *first;
    friend ostream& operator<< (ostream&, const Polynomal&);
    friend istream& operator>> (istream&, Polynomal&);
    friend Polynomal operator+ (Polynomal&, Polynomal&);
    friend Polynomal operator* (Polynomal&, Polynomal&);
};

Term* Term::InsertAfter(float c, int e)
{
    link = new Term(c, e);//此處和書上不同
    return link;
}


ostream& operator<<(ostream& out, const Term& x)
{
    if (x.coef != 1 || x.exp ==0)//此處和書上不同,如果係數為±1不顯示1.
    {
        if (x.coef == -1 && x.exp !=0)
            out << '-';
        else out << x.coef;
    }
    switch (x.exp)
    {
    case 0:
        break;
    case 1:
        out << "X";
        break;
    default:
        out << "X^" << x.exp;
        break;
    }
    return out;
}

Polynomal::Polynomal(Polynomal &R)
{
    first = new Term(0, -1);
    Term *destptr = first, *srcptr = R.getHead()->link;
    while(srcptr)
    {
        destptr->InsertAfter(srcptr->coef, srcptr->exp);
        srcptr = srcptr->link;
        destptr = destptr->link;
    }
}

int Polynomal::maxOrder()
{
    Term *current = first;
    while (current->link)
        current = current->link;
    return current->exp;
}

istream& operator>> (istream& in, Polynomal &x)
{
    Term *rear = x.getHead();
    int c, e;//c不應該是float麼?
    while (1)
    {
        cout << "Input a term(coef,exp):" << endl;
        in >> c >> e;
        if (e < 0)
            break;
        rear = rear->InsertAfter(c,e);
    }
    return in;
}

ostream& operator<< (ostream& out, Polynomal &x)
{
    Term *current = x.getHead()->link;
    cout << "The polynomal is : " << endl;
    bool h = true;
    while (current)
    {
        if (h == false && current->coef>0.0)
            out << "+";
        h = false;
        out << *current;
        current = current->link;
    }
    out << endl;
    return out;
}

Polynomal operator+ (Polynomal &A, Polynomal &B)
{
    Term *pa, *pb, *pc, *p;
    float temp;
    Polynomal C;
    pc = C.first;
    pa = A.getHead()->link;
    pb = B.getHead()->link;
    while (pa && pb)
    {
        if (pa->exp == pb->exp)
        {
            temp = pa->coef + pb->coef;
            if (temp > 0.001 || temp < -0.001)//fabs還要包含標頭檔案,麻煩..
                pc = pc->InsertAfter(temp,pa->exp);
            pa = pa->link;
            pb = pb->link;
        }
        else if (pa->exp < pb->exp)
        {
            pc = pc->InsertAfter(pa->coef, pa->exp);
            pa = pa->link;
        }
        else
        {
            pc = pc->InsertAfter(pb->coef, pb->exp);
            pb = pb->link;
        }
    }
    if (pa)
        p = pa;
    else p = pb;
    while (p)
    {
        pc = pc->InsertAfter(p->coef, p->exp);
        p = p->link;
    }
    return C;
}

Polynomal operator* (Polynomal &A, Polynomal &B)
{
    Term *pa, *pb, *pc;
    int AL, BL, i, k, maxExp;
    Polynomal C;
    pc = C.getHead();
    AL = A.maxOrder();
    BL = B.maxOrder();
    if (AL != -1 || BL != -1)
    {
        maxExp = AL + BL;
        float *result = new float[maxExp+1];
        for ( i = 0; i <= maxExp; ++i)
            result[i] = 0.0;
        pa = A.getHead()->link;
        while (pa)
        {
            pb = B.getHead()->link;
            while (pb)
            {
                k = pa->exp + pb->exp;
                result[k] = result[k] + pa->coef*pb->coef;
                pb = pb->link;
            }
            pa = pa->link;
        }
        for (i = 0; i <= maxExp; ++i)
        if (result[i] > 0.001 || result[i] < -0.001)//同上
            pc = pc->InsertAfter(result[i],i);
        delete [] result;
    }
    pc->link = 0;
    return C;
}

int main()
{
    Polynomal A;
    cout << "Input A:\n";
    cin >> A;
    cout << A;
    Polynomal B;
    cout << "Input B:\n";
    cin >> B;
    Polynomal C;
    C = A+B;
    Polynomal D;
    D = A*B;
    cout << "A: " << A << "B: " << B
         << "A+B: " << C << "A*B: " << D;
}