c语言 求两个多项式的乘积(1)编写函数实现一个多项式的输入,返回多项式链表的头指针。(2)编写函数实现两个多项式相乘,返回结果多项式链表的头指针。(3)编写函数输出一个多项式的二元组序列。(4)在main函数

中调用以上函数，实现两个多项式的输入和输出结果。

以下是实现代码：

#include <stdio.h>
#include <stdlib.h>

typedef struct PolyNode *PtrToPolyNode;
struct PolyNode {
    int coef; // 系数
    int expon; // 指数
    PtrToPolyNode next; // 下一项
};

typedef PtrToPolyNode Polynomial;

Polynomial CreatePoly(); // 创建多项式
Polynomial PolyAdd(Polynomial P1, Polynomial P2); // 多项式加法
Polynomial PolyMultiply(Polynomial P1, Polynomial P2); // 多项式乘法
void PrintPoly(Polynomial P); // 输出多项式

int main()
{
    Polynomial P1, P2, PMul;
    P1 = CreatePoly();
    P2 = CreatePoly();
    PMul = PolyMultiply(P1, P2);
    printf("P1: ");
    PrintPoly(P1);
    printf("P2: ");
    PrintPoly(P2);
    printf("P1 * P2: ");
    PrintPoly(PMul);
    return 0;
}

Polynomial CreatePoly()
{
    int n, coef, expon;
    PtrToPolyNode p, rear, head;
    head = (Polynomial)malloc(sizeof(struct PolyNode));
    head->next = NULL;
    rear = head;
    scanf("%d", &n);
    while (n--) {
        scanf("%d %d", &coef, &expon);
        p = (PtrToPolyNode)malloc(sizeof(struct PolyNode));
        p->coef = coef;
        p->expon = expon;
        p->next = NULL;
        rear->next = p;
        rear = p;
    }
    return head;
}

Polynomial PolyAdd(Polynomial P1, Polynomial P2)
{
    Polynomial P, rear, t1, t2, p;
    P = (Polynomial)malloc(sizeof(struct PolyNode));
    P->next = NULL;
    rear = P;
    t1 = P1->next;
    t2 = P2->next;
    while (t1 && t2) {
        if (t1->expon > t2->expon) {
            p = (PtrToPolyNode)malloc(sizeof(struct PolyNode));
            p->coef = t1->coef;
            p->expon = t1->expon;
            p->next = NULL;
            rear->next = p;
            rear = p;
            t1 = t1->next;
        } else if (t1->expon < t2->expon) {
            p = (PtrToPolyNode)malloc(sizeof(struct PolyNode));
            p->coef = t2->coef;
            p->expon = t2->expon;
            p->next = NULL;
            rear->next = p;
            rear = p;
            t2 = t2->next;
        } else {
            if (t1->coef + t2->coef != 0) {
                p = (PtrToPolyNode)malloc(sizeof(struct PolyNode));
                p->coef = t1->coef + t2->coef;
                p->expon = t1->expon;
                p->next = NULL;
                rear->next = p;
                rear = p;
            }
            t1 = t1->next;
            t2 = t2->next;
        }
    }
    while (t1) {
        p = (PtrToPolyNode)malloc(sizeof(struct PolyNode));
        p->coef = t1->coef;
        p->expon = t1->expon;
        p->next = NULL;
        rear->next = p;
        rear = p;
        t1 = t1->next;
    }
    while (t2) {
        p = (PtrToPolyNode)malloc(sizeof(struct PolyNode));
        p->coef = t2->coef;
        p->expon = t2->expon;
        p->next = NULL;
        rear->next = p;
        rear = p;
        t2 = t2->next;
    }
    return P;
}

Polynomial PolyMultiply(Polynomial P1, Polynomial P2)
{
    Polynomial P, rear, t1, t2, p;
    int coef, expon;
    if (!P1 || !P2)
        return NULL;
    t1 = P1->next;
    t2 = P2->next;
    P = (Polynomial)malloc(sizeof(struct PolyNode));
    P->next = NULL;
    rear = P;
    while (t2) {
        p = (Polynomial)malloc(sizeof(struct PolyNode));
        p->coef = t1->coef * t2->coef;
        p->expon = t1->expon + t2->expon;
        p->next = NULL;
        rear->next = p;
        rear = p;
        t2 = t2->next;
    }
    t1 = t1->next;
    while (t1) {
        t2 = P2->next;
        rear = P;
        while (t2) {
            expon = t1->expon + t2->expon;
            coef = t1->coef * t2->coef;
            while (rear->next && rear->next->expon > expon) {
                rear = rear->next;
            }
            if (rear->next && rear->next->expon == expon) {
                if (rear->next->coef + coef != 0) {
                    rear->next->coef += coef;
                } else {
                    p = rear->next;
                    rear->next = p->next;
                    free(p);
                }
            } else {
                p = (Polynomial)malloc(sizeof(struct PolyNode));
                p->coef = coef;
                p->expon = expon;
                p->next = rear->next;
                rear->next = p;
            }
            t2 = t2->next;
        }
        t1 = t1->next;
    }
    p = P;
    P = P->next;
    free(p);
    return P;
}

void PrintPoly(Polynomial P)
{
    if (!P) {
        printf("0 0\n");
        return;
    }
    PtrToPolyNode p = P->next;
    if (!p) {
        printf("0 0\n");
        return;
    }
    while (p) {
        printf("%d %d", p->coef, p->expon);
        p = p->next;
        if (p) {
            printf(" ");
        } else {
            printf("\n");
        }
    }
}

以上代码实现了多项式的输入、加法、乘法和输出操作。在 `main` 函数中，调用 `CreatePoly()` 函数输入两个多项式，再调用 `PolyMultiply()` 函数求出它们的乘积，最后分别调用 `PrintPoly()` 函数输出三个多项式。