用于記錄答案
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系數和指數（絕對值均為不超過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系數和指數。數字間以空格分隔，但結尾不能有多余空格。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

include<stdio.h>

include<stdlib.h>

typedef struct Node *PtrToNode;
struct Node{
int Exponential;
int Coefficient;
PtrToNode Next;
};
typedef PtrToNode Polynomial;

void Attach(int c, int e, Polynomial pRear) {
Polynomial P;
P = (Polynomial)malloc(sizeof(struct Node));
P->Coefficient = c;
P->Exponential = e;
P->Next = NULL;
(pRear)->Next = P;
(*pRear) = P;
}

Polynomial readPolynomial() {
Polynomial P, Rear, t;
int num, c, e;
P = (Polynomial)malloc(sizeof(struct Node));
P->Next = NULL;
Rear = P;
scanf("%d", &num);

while (num--) {
    scanf("%d %d", &c, &e);
    Attach(c, e, &Rear);
}
t = P;P = P->Next; free(t);
return P;

}

Polynomial plus(Polynomial p1, Polynomial p2) {
Polynomial po1 = p1;
Polynomial po2 = p2;
Polynomial sum = (Polynomial)malloc(sizeof(struct Node));
sum->Next = NULL;
Polynomial plus = sum;
Polynomial t;
while(po1!=NULL && po2!=NULL) {
if(po1->Exponential==po2->Exponential) {
int sum = po1->Coefficient + po2->Coefficient;
if(sum){
Attach(sum, po1->Exponential, &plus);
}
po1 = po1->Next;
po2 = po2->Next;
} else if (po1->Exponential >po2->Exponential) {
Attach(po1->Coefficient, po1->Exponential, &plus);
po1 = po1->Next;
} else {
Attach(po2->Coefficient, po2->Exponential, &plus);
po2 = po2->Next;
}
}
while(po1!=NULL) {
Attach(po1->Coefficient, po1->Exponential, &plus);
po1 = po1->Next;
}
while(po2!=NULL) {
Attach(po2->Coefficient, po2->Exponential, &plus);
po2 = po2->Next;
}
plus ->Next = NULL;
t = sum;
sum = sum->Next;
free(t);
return sum;
}

void addToPolynomial(Polynomial *P,Polynomial *product) {
Polynomial temp = *product;
Polynomial unitP = *P;

while (temp->Next !=NULL) {
    if (temp->Next->Exponential < unitP->Exponential) {
        unitP->Next = temp->Next;
        temp->Next = unitP;
        return;
    } else if (temp->Next->Exponential > unitP->Exponential) {
        temp = temp->Next;
    } else {
        int t = temp->Next->Coefficient + unitP->Coefficient;
        if (t == 0) {
            temp->Next = temp->Next->Next;
            free(unitP);
            return;
        } else {
            temp->Next->Coefficient = t;
            free(unitP);
            return;
        }
    }
}

if (temp->Next == NULL) {
    temp->Next = unitP;
}

}

void printPolynomial(Polynomial pol) {
int flag = 0;
if (pol == NULL) {
printf("%d %d", 0, 0);
}

while(pol != NULL){
    if (!flag) {
        printf("%d %d", pol->Coefficient, pol->Exponential);
        flag = 1;
    } else{
        printf(" %d %d", pol->Coefficient, pol->Exponential);
    }
    pol = pol->Next;
}

}

Polynomial multiply(Polynomial po1, Polynomial po2) {
Polynomial product,p1, p2, rear, t;
p1 = po1;
p2 = po2;
if (p1==NULL || p2 ==NULL) {
return NULL;
}
product = (Polynomial)malloc(sizeof(struct Node));
rear = product;
rear->Next = NULL;
while(po2!=NULL) {
Polynomial P = malloc(sizeof(struct Node));
P->Coefficient = po1->Coefficient * po2->Coefficient;
P->Exponential = po1->Exponential + po2->Exponential;
P->Next = NULL;
rear->Next = P;
po2 = po2->Next;
rear = rear->Next;
}
while (po1->Next!=NULL) {
po1 = po1->Next;
po2 = p2;
while (po2!=NULL) {
Polynomial P = malloc(sizeof(struct Node));
P->Coefficient = po1->Coefficient * po2->Coefficient;
P->Exponential = po1->Exponential + po2->Exponential;
P->Next = NULL;
addToPolynomial(&P, &product);
po2 = po2->Next;
}
}
if (product->Next == NULL) {
product->Exponential = 0;
product->Coefficient = 0;
} else{
t = product;
product = product->Next;
free(t);
}
return product;
}

int main() {
//todo 判0多項式輸入，常熟多項式
Polynomial P1 = readPolynomial();
Polynomial P2 = readPolynomial();

Polynomial Sum = plus(P1, P2);
Polynomial Product = multiply(P1, P2);

printPolynomial(Product);
printf("\n");
printPolynomial(Sum);

return 0;

}