02-線性結構2 一元多項式的乘法與加法運算 | 陳越、何欽銘-數據結構

02-線性結構2 一元多項式的乘法與加法運算

設計函數分別求兩個一元多項式的乘積與和。

輸入格式:

輸入分2行，每行分別先給出多項式非零項的個數，再以指數遞降方式輸入一個多項式非零項係數和指數（絕對值均爲不超過1000的整數）。數字間以空格分隔。

輸出格式:

輸出分2行，分別以指數遞降方式輸出乘積多項式以及和多項式非零項的係數和指數。數字間以空格分隔，但結尾不能有多餘空格。零多項式應輸出0 0。

輸入樣例:

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

輸出樣例:

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

代碼：

嗚嗚嗚這題我抄寫了好多遍，最後迴歸刷老師的視頻，把視頻裏提到的函數拼在一起才做出來的。

#include <stdio.h>
#include <stdlib.h>
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; //第一項就什麼都不做
        else
            printf(" "); //不是第一項就輸出空格
        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;
}

大家也可以借鑑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

另外我終於會用MAC的終端寫和編譯運行C代碼，感謝這位大佬：
https://blog.csdn.net/kisssfish/article/details/80557391