PTA7-2一元多项式的乘法与加法运算

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<stdlib.h>
typedef struct poly
{
    int coef;
    int exp;
    struct poly *next;
}POLY;
POLY *Input(POLY *p);
void Display(POLY *p);
POLY *Add(POLY *p1,POLY *p2);
void Descend(POLY *&p);
POLY *Multiply(POLY *p1,POLY *p2);
int main()
{
    POLY *p1=NULL,*p2=NULL,
         *sum=NULL,*mul=NULL;
    int n1,n2;
    p1=Input(p1);
    p2=Input(p2);
    mul=Multiply(p1,p2);
    //printf("*******");
    sum=Add(p1,p2);
    //printf("\n*******");
    Display(mul);
    printf("\n");
    Display(sum);
}
POLY *Input(POLY *p)
{
    int n;
    scanf("%d",&n);
    p=(POLY *)malloc(sizeof(POLY));
    POLY *temp=NULL,*p2=p;
    for(int i=0;i<n;i++)
    {
        temp=(POLY *)malloc(sizeof(POLY));
        temp->next=NULL;
        scanf("%d",&temp->coef);
        scanf("%d",&temp->exp);
        p2->next=temp;
        p2=p2->next;
    }
    return p;
}
void Display(POLY *p)
{
    if(p->next->next==NULL&&p->next->coef==0)
    {
        printf("0 0");
    }
    else
    {
         while(p->next->next!=NULL)
         {
            printf("%d %d ",p->next->coef,p->next->exp);
            p=p->next;
         }
         printf("%d %d",p->next->coef,p->next->exp);
    }
}
POLY *Add(POLY *p1,POLY *p2)
{
    POLY *p=NULL,*temp=NULL,*pr=NULL;
    p=(POLY *)malloc(sizeof(POLY));
    pr=p;
    while(p1->next!=NULL||p2->next!=NULL)
    {
        temp=(POLY *)malloc(sizeof(POLY));
        temp->next=NULL;
        pr->next=temp;
        if(p1->next!=NULL)
        {
            temp->coef=p1->next->coef;
            temp->exp=p1->next->exp;
            p1=p1->next;
        }
        else if(p2->next!=NULL)
        {
            temp->coef=p2->next->coef;
            temp->exp=p2->next->exp;
            p2=p2->next;
        }
        pr=pr->next;
    }   
    //printf("****");
    Descend(p);
    return p;
}
void Descend(POLY *&p)
{
    POLY *p1=(POLY *)malloc(sizeof(POLY));
    POLY *pr=p,*temp=NULL,*pr2=p1;
    while(pr->next!=NULL)
    {
        temp=(POLY *)malloc(sizeof(POLY));
        temp->next=NULL;
        pr2->next=temp;
        temp->coef=pr->next->coef;
        temp->exp=pr->next->exp;
        pr=pr->next;
        pr2=pr2->next;
    }
    pr=p;
    pr2=p1;
    POLY temp2;
    while(pr2->next->next!=NULL)
    {
        pr=p;
        while(pr->next->next!=NULL)
        {
            if(pr->next->exp<pr->next->next->exp)
            {
                temp2.coef=pr->next->coef;
                temp2.exp=pr->next->exp;
                pr->next->coef=pr->next->next->coef;
                pr->next->exp=pr->next->next->exp;
                pr->next->next->coef=temp2.coef;
                pr->next->next->exp=temp2.exp;
            }
            pr=pr->next;
        }
        pr2=pr2->next;
    }
    pr=p;
    pr2=p1;
    while(pr->next!=NULL)
    {
        if(pr->next->coef==0&&p->next->next!=NULL)
        {
            pr->next=pr->next->next;
        }
        else
            pr=pr->next;
    }
    pr=p;
    pr2=p1;
    while(pr->next->next!=NULL)
    {
        temp=pr->next->next;
        if(pr->next->exp==pr->next->next->exp)
        {
             pr->next->coef=pr->next->coef+pr->next->next->coef;
             pr->next->next=temp->next;
             free(temp);
            if(pr->next->coef==0&&p->next->next!=NULL)
            {
                pr->next=pr->next->next;
            }
        }
        else
            pr=pr->next;
    }
}
POLY *Multiply(POLY *p1,POLY *p2)
{
    POLY *p=(POLY *)malloc(sizeof(POLY));
    POLY *temp=NULL,*pr=p,*p2_temp=p2;
    while(p1->next!=NULL)
    {
        p2=p2_temp;
        while(p2->next!=NULL)
        {
            temp=(POLY *)malloc(sizeof(POLY));
            temp->coef=p1->next->coef*p2->next->coef;
            temp->exp=p1->next->exp+p2->next->exp;
            temp->next=NULL;
            pr->next=temp;
            pr=pr->next;
            p2=p2->next;
        }
        p1=p1->next;
    }
    Descend(p);
    return p;
}