02-线性结构2 一元多项式的乘法与加法运算 | 陈越、何钦铭-数据结构

02-线性结构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。

输入样例:

4 3 4 -5 2 6 1 -2 0
3 5 20 -7 4 3 1

输出样例:

15 24 -25 22 30 21 -10 20 -21 8 35 6 -33 5 14 4 -15 3 18 2 -6 1
5 20 -4 4 -5 2 9 1 -2 0

代码：

呜呜呜这题我抄写了好多遍，最后回归刷老师的视频，把视频里提到的函数拼在一起才做出来的。

#include 
#include 
typedef struct PolyNode *Polynomial;

struct PolyNode{
    int coef;
    int expon;
    Polynomial link;
};


Polynomial ReadPoly();
void PrintPoly(Polynomial P);
void Attach(int c, int e, Polynomial *pRear);
Polynomial Mult(Polynomial P1, Polynomial P2);
Polynomial Add(Polynomial P1, Polynomial P2);

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;
}


Polynomial ReadPoly(){
    Polynomial P, Rear, t;
    int c,e, N;
    
    scanf("%d",&N);
    P = (Polynomial)malloc(sizeof(struct PolyNode));
    P->link = NULL;
    Rear = P;
    
    while(N--){
        scanf("%d%d", &c, &e);
        Attach(c,e,&Rear);
    }
    t=P;
    P=P->link;
    free(t);
    return P;
}

void Attach(int c, int e, Polynomial *pRear){
    Polynomial P;
    P = (Polynomial)malloc(sizeof(struct PolyNode));
    P->coef = c;
    P->expon = e;
    P->link = NULL;
    (*pRear)->link = P;
    *pRear = P;
}

void PrintPoly(Polynomial P){
    int flag = 0;
    if(!P){
        printf("0 0\n");
        return;
    }
    while(P){
        if(!flag)
            flag=1; //第一项就什么都不做
        else
            printf(" "); //不是第一项就输出空格
        printf("%d %d", P->coef,P->expon);
        P=P->link;
    }
    printf("\n");
}


Polynomial Add(Polynomial P1, Polynomial P2){
    Polynomial t1,t2,P,rear,t;
    int sum;
    
    t1=P1; t2=P2;
    P=(Polynomial)malloc(sizeof(struct PolyNode));
    P->link = NULL;
    rear = P;
    while(t1 && t2){
        if(t1->expon == t2->expon){
            sum=t1->coef + t2->coef;
            if(sum)
                Attach(sum, t1->expon, &rear);
            t1=t1->link;
            t2=t2->link;
        }else if(t1->expon > t2->expon){
            Attach(t1->coef, t1->expon, &rear);
            t1=t1->link;
        }else{
            Attach(t2->coef, t2->expon, &rear);
            t2=t2->link;
        }
    }
    while(t1){
        Attach(t1->coef, t1->expon, &rear);
        t1=t1->link;
    }
    while(t2){
        Attach(t2->coef, t2->expon, &rear);
        t2=t2->link;
    }
    rear->link=NULL;
    t=P;
    P=P->link;
    free(t);
    return P;
    
}



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));
    Rear = P;
    while(t2){
        Attach(t1->coef*t2->coef, t1->expon+t2->expon, &Rear);
        t2=t2->link;
    }
    t1 = t1->link;
    while(t1){
        t2=P2; Rear=P;
        while(t2){
            c = t1->coef*t2->coef;
            e = t1->expon + t2->expon;
            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;
}

大家也可以借鉴一下各位大佬的答案：
https://blog.csdn.net/u011638313/article/details/52777128
https://blog.csdn.net/afishfly/article/details/89000322

另外我终于会用MAC的终端写和编译运行C代码，感谢这位大佬：
https://blog.csdn.net/kisssfish/article/details/80557391