两个多项式相加及相乘

#include <stdio.h>#include <malloc.h>  typedef struct PolyNode *Polynomial; struct PolyNode{    int coef;    int expon;    Polynomial link; }; 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; //修改pRear的值     *pRear=P; } Polynomial ReadPoly() {    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); //将当前项插入多项式尾部      }     t=P;P=P->link;free(t); //删除临时生成的头结点      return P; } Polynomial Add(Polynomial P1,Polynomial P2) {    Polynomial front,rear,temp;    int sum;    rear=(Polynomial)malloc(sizeof(struct PolyNode));    front=rear; /*由front记录结果多项式链表头结点*/    while(P1&&P2){ /*当两个多项式都有非零项待处理时*/         if(P1->expon==P2->expon){            sum=P1->coef+P2->coef;            if(sum){            Attach(sum,P1->expon,&rear);            P1=P1->link;            P2=P2->link;            }else{                P1=P1->link;                P2=P2->link;             }         }else if(P1->expon>P2->expon){            Attach(P1->coef,P1->expon,&rear);            P1=P1->link;         }else{            Attach(P2->coef,P2->expon,&rear);            P2=P2->link;         }     }     /*将未处理完的另一个多项式的所有节点依次复制到结果多项式中去*/      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; /*令front指向结果多项式第一个非零项*/     free(temp);        /*释放临时空表头结点*/     return front;  } /*采用逐项插入的方法，将P1当前项乘以P2的当前项，并插入到结果多项式中，关键是要找到插入的位置*/  /*初始结果多项式由P1第一项乘以P2各项获得*/ 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){ //P1第一项乘以P2各项得到初始结果多项式         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;            //printf("%d,%d\n",Rear->coef,Rear->expon);        }        t1=t1->link;     }    t2=P;P=P->link;free(t2);    return P;} void PrintPoly(Polynomial P) {    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;     } }  int main() {    Polynomial P1,P2,PS,PP;    P1=ReadPoly();    P2=ReadPoly();    PP=Mult(P1,P2);    PrintPoly(PP);    printf("\n");    PS=Add(P1,P2);    PrintPoly(PS);     return 0; }/* 测试数据4 3 5 2 4 3 3 6 13 2 5 3 4 4 3*/