一元多项式加法与乘法运算链表实现

typedef struct PolyNode *Polynomial;
struct PolyNode{
int coef;//系数
int expon;//指数
Polynomial link;/*指向下一个结点的指针*/
};
Polynomial P,Rear,t1,t2,t;//这句一定要写

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;
}
void Attach(int c,int e,Polynomial *pRear)//*pRear是指针的指针
{
Polynomial P;

P=(Polynomial)malloc(sizeof(struct PolyNode));
P->coef=c;//对新结点赋值
P->expon=e;
P->link=NULL;
(*pRear)->link=P;
*pRear=P;//修改pRear的值
}
Polynomial ReadPoly()//读入多项式
{
Polynomial P,Rear,t;
int c,e,N;
scanf("%d",&N);
P=(Polynomial)malloc(sizeof(struct PolyNode));//链表头空结点
P->link=NULL;
Rear=P;
while(N--){
scanf("%d %d",&c,&e);
Attach(c,e,&Rear);//将当前插入多项式尾部
}
t=P;P=P->link; free(t);//删除临时生成的头结点
return P;
}
Polynomial Mult(Polynomial P1,Polynomial P2)//如何将两个多项式相乘
{
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){
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)
{//输出多项式
int flag=0;//辅助调整输出格式用
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");
}