c语言链表实现一元多项式的加减乘运算

#include <stdio.h>
#include <stdlib.h>
#define SHI sizeof(struct duoxiangshi)
#define NULL 0
struct duoxiangshi
{int xishu,zhishu;
 struct  duoxiangshi*next;
};


struct duoxiangshi*create()                  
{struct duoxiangshi*head,*p1,*p2;
 int n;
 n=0;
 head=NULL;
 p2=NULL;
 p1=NULL;
 p1=(struct duoxiangshi*)malloc(SHI);          
 scanf("%d %d",&p1->xishu,&p1->zhishu);
 while(p1->xishu!=NULL)
 {++n;
  if(n==1){head=p1;p2=p1;}
  else{p2->next=p1;p2=p1,p2->next=NULL;}
  p1=(struct duoxiangshi*)malloc(SHI);
  scanf("%d %d",&p1->xishu,&p1->zhishu);
  p1->next=NULL;
 }
 free(p1);          
 return (head);
}
 
  void paixu(struct duoxiangshi*head)       
{struct duoxiangshi*p1,*p2;
 int t=0;
 p1=head;
 p2=head;
 for( ; ;p1=p1->next)
 {  if(p1->next==NULL)break;
    for(p2=p1->next; ;p2=p2->next)
  {   if(p1->zhishu>p2->zhishu)
   {   t=p1->zhishu;
    p1->zhishu=p2->zhishu;
    p2->zhishu=t;
    
    t=p1->xishu;
    p1->xishu=p2->xishu;
    p2->xishu=t;
   }
  
  if(p2->next==NULL)break;
  }
 }
}

 

struct duoxiangshi*add(struct duoxiangshi*head1,struct duoxiangshi*head2)          
{struct duoxiangshi*p1,*p2,*s,*p3,*head3;
 int n=1;
 p1=head1;
 p2=head2;
 head3=NULL;
 p3=NULL;
 while(p1!=NULL&&p2!=NULL)
 {s=(struct duoxiangshi*)malloc(SHI);
  ++n;
  if(n==1) head3=s;
  if(p1->zhishu>p2->zhishu)       
  {s->zhishu=p2->zhishu;
   s->xishu=p2->xishu;
   p2=p2->next;                
  }
  else if(p1->zhishu<p2->zhishu)           
  {s->zhishu=p1->zhishu;
   s->xishu=p1->xishu;
   p1=p1->next;            
  }
  else
  {s->zhishu=p1->zhishu;                              
   s->xishu=p1->xishu+p2->xishu;               
   p1=p1->next;           
   p2=p2->next;
  }
  p3->next=s;
  p3=s;
  
 }
 p3->next=NULL;
 if(p1!=NULL)                
  p3->next=p1;
 if(p2!=NULL)
  p3->next=p2;
 return (head3);    
} 


struct duoxiangshi* minus(struct duoxiangshi*head1,struct duoxiangshi*head2)        
{struct duoxiangshi*p2;
 p2=head2;
 while(p2!=NULL)
    {p2->xishu=(-1)*p2->xishu;                      
 p2=p2->next;
 }
 return (add(head1,head2));                     
}


 struct duoxiangshi* multiply(struct duoxiangshi*px,struct duoxiangshi*py)      
{   int n=0,i=0,j=0;
 struct duoxiangshi*heada,*headb,*pa,*pb,*lasta,*lastb,*p2,*p1;
 p1=heada=headb=pa=pb=lasta=lastb=NULL;
 p2=py;
 
 while (p2!=NULL)
 {n++;
  if(n==1)              
  {  p1=px;
   while(p1!=NULL)
   {i++;
    pa=(struct duoxiangshi*)malloc(SHI);
    if(i==1) heada=pa;               
    else lasta->next=pa;
    lasta=pa;
    pa->xishu=p1->xishu*p2->xishu;                
    pa->zhishu=p1->zhishu+p2->zhishu;           
    pa->next=NULL;
    p1=p1->next;                          
   }
  }
  else                  
  { p1=px;
   while(p1!=NULL)
   {j++;
    pb=(struct duoxiangshi*)malloc(SHI);
    if(j==1) headb=pb;
    else lastb->next=pb;
    lastb=pb;
    pb->xishu=p1->xishu*p2->xishu;
    pb->zhishu=p1->zhishu+p2->zhishu;
    pb->next=NULL;
    p1=p1->next;
   }
   
  }
  p2=p2->next;
  if(n!=1)heada=add(heada,headb);     
 }
  return(heada);  
    
     
}


void print (struct duoxiangshi*head3)       
{struct duoxiangshi*p3;
 p3=head3;
 
 do
 {  if(p3->zhishu==0)   
  {printf("%d",p3->xishu);    
   p3=p3->next;
   continue;
  }
  else if(p3==head3)          
    {printf("%dx%d",p3->xishu,p3->zhishu);
   p3=p3->next;
   continue;
  }
  else if(p3->xishu<0)      
  printf("%dx%d",p3->xishu,p3->zhishu);
  else if(p3->xishu>0)      
  printf("+%dx%d",p3->xishu,p3->zhishu);
  p3=p3->next;
 }while(p3!=NULL);
 printf("\n\n");
}
 


void main()
{struct duoxiangshi*p1,*p2,*p3;
 int c=0;char d;
   do
    {
    

 printf("please input A:\n");        
 p1=create();
 paixu(p1);
 printf("\nthe A is:");
 print(p1);
 
 
 printf("please input B:\n");
 p2=create();
 paixu(p2);
 printf("\nthe B is:");
 print(p2);
 
 printf("\n      please choice :\n");
 printf("*********************************\n");
 printf("1.add     2.minu     3.multiply\n");
 printf("*********************************\n");
 scanf("%d",&c);
 switch(c)
 {case 1:p3=add(p1,p2);break;
  case 2:p3=minus(p1,p2);break;
  case 3:p3=multiply(p1,p2);break;
  default:printf("\nerror");
  
 }
 printf("\nthe result is :");
 print(p3);
 printf("do you still have anything to do?(y/n):\n");
 scanf("%c",&d);
 getchar();
 clrscr();

}while(d!='n'&&d!='N');

}