02-线性结构2 一元多项式的乘法与加法运算 （20 分）

设计函数分别求两个一元多项式的乘积与和。

输入格式:

输入分2行，每行分别先给出多项式非零项的个数，再以指数递降方式输入一个多项式非零项系数和指数（绝对值均为不超过1000的整数）。数字间以空格分隔。

输出格式:

输出分2行，分别以指数递降方式输出乘积多项式以及和多项式非零项的系数和指数。数字间以空格分隔，但结尾不能有多余空格。零多项式应输出0 0。

#include <stdio.h>
#include <time.h>
#include <math.h>
#include <stdlib.h>
typedef struct PolyNode *Polynomial;
struct PolyNode{
    int coef;
    int expon;
    Polynomial link;
};
Polynomial ReadPoly();
void Attach(int c,int e,Polynomial *pRear);
Polynomial Add(Polynomial P1,Polynomial P2);
Polynomial Mult(Polynomial P1,Polynomial P2);
void PrintPoly (Polynomial P);


int main()
{
    Polynomial P1,P2,PP,PS;

    P1=ReadPoly();
    P2=ReadPoly();
    PP=Mult(P1,P2);
    PrintPoly(PP);
    PS=Add(P1,P2);
    PrintPoly(PS);
    return 0;
}

Polynomial ReadPoly()
{
    Polynomial P,Rear,t;
    int c,e,N;
    scanf("%d",&N);
    P=(Polynomial)malloc(sizeof(struct PolyNode));
    P->link=NULL;                        //链表的空结点
    Rear=P;
    while(N--){
        scanf("%d %d",&c,&e);
        Attach(c,e,&Rear);
        //printf("t->coef= %d t->expon= %d",)
    }
    t=P;P=P->link;
    //for(;t;t=t->link)
        //printf(" t->coef= %d t->expon= %d ",t->coef,t->expon);
    free(t);                     //删除临时生成的空结点

    return P;
}
void Attach(int c,int e,Polynomial *pRear)
{
    Polynomial P;
    P=(Polynomial)malloc(sizeof(struct PolyNode));    //生成新节点
    P->coef=c;
    P->expon=e;
    P->link=NULL;
    (*pRear)->link=P;                          //需要修改指针本身存放的地址，参数用&
    *pRear=P;
}
Polynomial Add(Polynomial P1,Polynomial P2)
{
    Polynomial P,Rear,t1,t2,t;
    t1=P1;t2=P2;
    P=(Polynomial)malloc(sizeof(struct PolyNode));
    P->link=NULL;
    Rear =P;
    while(t1&&t2){
        if(t1->expon==t2->expon){
            if(t1->coef+t2->coef)
            {
                Attach(t1->coef+t2->coef,t1->expon,&Rear);
                t1=t1->link;t2=t2->link;
            }
            else
            {
                t=t1;
                t1=t1->link;
                free(t);
                t=t2;
                t2=t2->link;
                free(t);
            }
        }
        else if(t1->expon>t2->expon){
            Attach(t1->coef,t1->expon,&Rear);
            t1=t1->link;
        }
        else {
            Attach(t2->coef,t2->expon,&Rear);
            t2=t2->link;
        }

        }
        while(t1){
            Attach(t1->coef,t1->expon,&Rear);
            t1=t1->link;

        }
        while(t2){
            Attach(t2->coef,t2->expon,&Rear);
            t2=t2->link;
        }
        t=P;P=P->link;free(t);
        return P;
}

Polynomial Mult(Polynomial P1,Polynomial P2)
{
    Polynomial P,Rear,t1,t2,t;
    int c,e;
    if(!P1||!P2)return NULL;
    t1=P1;t2=P2;
    P=(Polynomial)malloc(sizeof(struct PolyNode));
    P->link=NULL;
    Rear =P;

    while(t2){                  //先用p1的第一项乘以p2，得到p

        Attach(t1->coef*t2->coef,t1->expon+t2->expon,&Rear);
        t2=t2->link;
    }
    t1=t1->link;
    while(t1){
        t2=P2;Rear=P;
        while(t2){                           //插入到p中，考虑不同的情况
            e=t1->expon+t2->expon;
            c=t1->coef*t2->coef;
            while(Rear->link&&Rear->link->expon>e)
                Rear=Rear->link;
            if(Rear->link&&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=(Polynomial)malloc(sizeof(struct 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=P->link;free(t2);
    return P;
}
void PrintPoly (Polynomial P)
{
    int flag=0;
    if(!P){
        printf("0 0\n");
        return;
    }
    while(P){
        if(!flag)
            flag=1;
        else
            printf(" ");
        printf("%d %d",P->coef,P->expon);
        P=P->link;
    }
    printf("\n");
}

输入样例:

4 3 4 -5 2  6 1  -2 0
3 5 20  -7 4  3 1

输出样例:

15 24 -25 22 30 21 -10 20 -21 8 35 6 -33 5 14 4 -15 3 18 2 -6 1
5 20 -4 4 -5 2 9 1 -2 0