02 - 线性结构 1 一元多项式的乘法与加法运算 (20 分)

 
 
include 
 
 
include 
 
 
//int *p 指向 int 类型
 // 前面加上 typedef 可以让 POINTER 指向 struct POLYNODE 类型
 typedef struct POLYNODE *POINTER;
 // 定义一个 struct 类型
 struct POLYNODE{
 int coef;
 int expon;
 POINTER link;
 };
 POINTER ReadPoly();
 void Attach(int c, int e, POINTER *pRear);
 POINTER Add(POINTER P1, POINTER P2);
 POINTER Mult(POINTER P1, POINTER P2);
 void PrintPoly(POINTER P);
 int main(){
 POINTER P1,P2,PM,PA;
 P1 =ReadPoly();
 P2 =ReadPoly();
 PM=Mult(P1,P2);
 PrintPoly(PM);
 PA =Add(P1,P2);
 PrintPoly(PA);
 return 0;
 }
 // 构造一个头结点，不断向后添加
 POINTER ReadPoly(){
 POINTER P,Rear,t;
 int c,e,N;
 scanf("%d",&N);
 P = (POINTER)malloc(sizeof(struct POLYNODE)); //?????????
 P->link = NULL;
 Rear = P;
 while(N--){
 scanf("%d %d",&c,&e);
 Attach(c,e,&Rear); //??????????????β??
 }
 t = P; P = P->link; free(t); //???????????????
 return P;
 }
 // 在尾指针后面不断添加
 //attach 方法的使用必须保证有一个空的头结点
 void Attach(int c, int e, POINTER pRear){
 POINTER P;
 P = (POINTER)malloc(sizeof(struct POLYNODE));
 P->coef = c;
 P->expon = e;
 P->link = NULL;
 (pRear)->link = P;
 pRear = P;
 }
 // 构造一个新链，不断
 POINTER Add(POINTER P1,POINTER P2){
 POINTER front,temp,rear;
 front = (POINTER)malloc(sizeof(struct POLYNODE));
 rear = front;
 while(P1&&P2){
 if(P1->expon>P2->expon){
 Attach(P1->coef,P1->expon,&rear);
 P1=P1->link;
 }else if(P1->exponexpon){
 Attach(P2->coef,P2->expon,&rear);
 P2=P2->link;
 }else {
 if(P2->coef+P1->coef){
 Attach(P2->coef+P1->coef,P2->expon,&rear);
 }
 P1=P1->link;
 P2=P2->link;
 }
 }
 while(P1){
 Attach(P1->coef,P1->expon,&rear);
 P1=P1->link;
 }
 while(P2){
 Attach(P2->coef,P2->expon,&rear);
 P2=P2->link;
 }
 rear->link=NULL;
 temp = front;
 front = front->link;
 free(temp);
 return front;
 }
 POINTER Mult(POINTER P1,POINTER P2){
 POINTER t1,t2,P,rear,temp;
 int c,e;
 if(!P1||!P2) return NULL;
 t1=P1;t2=P2;
 P = (POINTER)malloc(sizeof(struct POLYNODE));P->link=NULL;
 rear = P;
 while(t2){
 // 构造新链，先把 t1 的第一项依次与 t2 作用
 Attach(t1->coeft2->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;
 //while 循环时，使用 rear->link 方便
 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 {
 rear->link = rear->link->link;
 }
 }else{
 temp = (POINTER)malloc(sizeof(struct POLYNODE));
 temp->coef = c; temp->expon = e;
 temp->link = rear->link;
 rear->link = temp; rear = rear->link;
 }
 t2=t2->link;
 }
 t1=t1->link;
 }
 temp = P; P = P->link; free(temp);
 return P;
 }
 void PrintPoly(POINTER 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");
 }