多项式乘法与加法运算（链表实现）

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#include<iostream>using namespace std;typedef struct PolyNode *Polynomial;struct PolyNode{    int coef;    int expon;    Polynomial link;};void Attach(int c, int e, Polynomial *pRear){    Polynomial P;//这里有点小问题，按理说应该动态申请一块空间，可是加上P=new PolyNode后编译错误...也没太弄懂    P->coef = c;    P->expon = e;    P->link = NULL;    (*pRear)->link = P;    (*pRear) = P;}Polynomial Polyread(){    int N,c,e;    Polynomial Rear, P,t;    cin >> N;    P = new PolyNode;    P->link = NULL;    Rear = P;    while (N--){        cin >> c >> e;        Attach(c, e, &Rear);    }    t = P; P = P->link; delete t;//删除临时生成的头结点    return P;}Polynomial Add(Polynomial P1, Polynomial P2){    Polynomial t1, t2, Rear, P;    t1 = P1; t2 = P2;    P = new PolyNode;    P->link = NULL;    Rear = P;    while (t1&&t2){        if (t1->expon > t2->expon){            Attach(t1->coef, t1->expon, &Rear);            t1 = t1->link;        }        if (t1->expon < t2->expon){            Attach(t1->coef, t2->expon, &Rear);        }        if (t1->expon == t2->expon){            if (t1->expon + t2->expon){                Attach(t1->coef + t2->coef, t1->expon, &Rear);                t1 = t1->link; t2 = t2->link;            }        }    }    return P;}Polynomial Mult(Polynomial P1, Polynomial P2){    Polynomial t1, t2, Rear, P,t;    int c, e;    if (!P1 || !P2) return NULL;    t1 = P1; t2 = P2;    P = new PolyNode;    P->link = NULL;    Rear = P;    while (t2){        Attach(t1->coef*t2->coef, t1->expon + t2->expon, &Rear);            t2 = t2->link;    }    t1 = t1->link;    while (t1){        t2 = P2; Rear = P;        while (t2){            e = t1->expon + t2->expon;            c = t1->coef*t2->coef;            while (Rear->link&&Rear->link->expon > e)                Rear = Rear->link;            if (Rear->link->expon == e){                if (Rear->link->coef + c)                    Rear->link->coef += c;                else{                    t = Rear->link; Rear->link = t->link; free(t);                }            }            else{                t = new PolyNode;                t->coef = c; t->expon = e;                t->link = Rear->link;                Rear->link = t;                Rear = Rear->link;            }            t2 = t2->link;        }    t1 = t1->link;}      t2 = P; P->link = t2->link; delete t2;      return P;}void PrintPoly(Polynomial P){    int flag = 0;    if (!P) cout << 0 << 0 << endl;    while (P){        if (!flag) flag = 1;        else            cout << " ";        cout << P->coef << P->expon;        P = P->link;    }}int main(){    Polynomial P1, P2, PP, PS;    P1 = Polyread();    P2 = Polyread();    PP = Add(P1, P2);    PrintPoly(PP);    PS = Mult(P1, P2);    PrintPoly(PS);    return 0;}

代码并没有在编译器中实现，新手渣渣还在学习中，欢迎指正…

在网上看到的正确答案：

#include <iostream>#include <algorithm>#include <vector>using namespace std;typedef struct Term{    int coe;//系数    int exp;//指数    }Term;bool compare(Term a,Term b){    return a.exp>b.exp;}/*Term Mul(Term a,Term b){    a.coe = a.coe*b.coe;    a.exp = a.exp+b.exp;    return a;}*//*Term Add(Term a,Term b){    a.coe +=b.coe;    return a;}*/void print(Term a){    cout<<a.coe<<" "<<a.exp<<" ";}int main(){    vector<Term>    vec1;    vector<Term>    vec2;    vector<Term>    vec;    vector<Term>::iterator  it1,it2;    int N1,N2;    int coe,exp;    bool  flag = false;    Term t;    cin>>N1;    while(N1--)    {        cin>>coe>>exp;        t.coe = coe;        t.exp = exp;        vec1.push_back(t);    }    //for_each(vec1.begin(),vec1.end(),print);    //system("pause");    cin>>N2;    while(N2--)    {        cin>>coe>>exp;        t.coe = coe;        t.exp = exp;        vec2.push_back(t);    }    //for_each(vec2.begin(),vec2.end(),print);    //system("pause");    for (it1=vec1.begin();it1!=vec1.end();it1++)        for (it2=vec2.begin();it2!=vec2.end();it2++)        {            t.coe = it1->coe * it2->coe;            t.exp = it1->exp + it2->exp;                if (t.coe!=0)            vec.push_back(t);        }    sort(vec.begin(),vec.end(),compare);    for (it1 = vec.begin();it1!=vec.end();it1=it2)      {            for (it2 = it1+1;it2!=vec.end() &&it1->exp==it2->exp;it2++)                              it1->coe += it2->coe;            if (it1->coe!=0)            {                if (flag)                cout<<" ";                else                flag = true;                cout<<it1->coe<<" "<<it1->exp;            }                        }    if (vec1.size()==0)    {        cout<<"0 0";    }    cout<<endl;    flag = false;    for (it1=vec1.begin(),it2=vec2.begin();it1!=vec1.end()&&it2!=vec2.end();)    {        if (it1->exp >it2->exp)        {            if (flag)                cout<<" ";            else                flag = true;            cout<<it1->coe<<" "<<it1->exp;            it1++;        }        else if (it1->exp < it2->exp)        {            if (flag)                cout<<" ";            else                flag = true;            cout<<it2->coe<<" "<<it2->exp;            it2++;        }        else        {            if ((it1->coe+it2->coe))            {                if (flag)                    cout<<" ";                else                    flag = true;                cout<<it1->coe+it2->coe<<" "<<it1->exp;            }            it1++;            it2++;        }    }    if (it1==vec1.end())    {        while(it2!=vec2.end())        {            if (flag)                cout<<" ";            else                flag = true;            cout<<it2->coe<<" "<<it2->exp;            it2++;        }    }    if (it2==vec2.end())    {        while(it1!=vec1.end())        {            if (flag)                cout<<" ";            else                flag = true;            cout<<it1->coe<<" "<<it1->exp;            it1++;        }    }    if (flag==false)    cout<<"0 0";    cout<<endl;     //for_each(vec.begin(),vec.end(),print);    //system("pause");    return 0;}

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