用C语言编写一个程序，用单链表存储一元多项式，并实现两个一元多项式相乘的运算

在C语言中，我们可以使用结构体来表示多项式的系数和指数，并用单链表来存储多项式。这里是一个简单的示例，展示如何创建节点、构建链表以及实现两个多项式相乘的基本操作：

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

typedef struct Node {
    int coef; // 系数
    int exp;  // 指数
    struct Node* next;
} PolynomialNode;

// 创建新节点
PolynomialNode* createNode(int coef, int exp) {
    PolynomialNode* newNode = (PolynomialNode*)malloc(sizeof(PolynomialNode));
    newNode->coef = coef;
    newNode->exp = exp;
    newNode->next = NULL;
    return newNode;
}

// 添加多项式项到链表
void addTerm(PolynomialNode** head, int coef, int exp) {
    PolynomialNode* newNode = createNode(coef, exp);
    if (*head == NULL) {
        *head = newNode;
    } else {
        PolynomialNode* temp = *head;
        while (temp->next != NULL) {
            temp = temp->next;
        }
        temp->next = newNode;
    }
}

// 相似于Python的zip，合并两个多项式列表
void mergePolynomials(PolynomialNode** first, PolynomialNode** second, PolynomialNode** result) {
    PolynomialNode* fHead = *first, *fTail = NULL;
    PolynomialNode* sHead = *second, *sTail = NULL;
    
    while (fHead != NULL && sHead != NULL) {
        if (fHead->exp > sHead->exp) {
            addTerm(result, fHead->coef * sHead->coef, fHead->exp + sHead->exp);
            sHead = sHead->next;
        } else if (fHead->exp < sHead->exp) {
            addTerm(result, fHead->coef * sHead->coef, fHead->exp + sHead->exp);
            fHead = fHead->next;
        } else { // 如果指数相同，只取一次
            addTerm(result, fHead->coef * sHead->coef, fHead->exp);
            fHead = fHead->next;
            sHead = sHead->next;
        }
        
        if (fTail != NULL) {
            fTail->next = sHead;
            fTail = fTail->next;
        } else {
            *result = fHead;
        }
    }

    if (fHead != NULL) {
        while (fHead != NULL) {
            fTail = fHead;
            fHead = fHead->next;
            addTerm(result, fTail->coef, fTail->exp);
        }
    } else if (sHead != NULL) {
        while (sHead != NULL) {
            fTail = sHead;
            sHead = sHead->next;
            addTerm(result, fTail->coef, fTail->exp);
        }
    }
}

int main() {
    PolynomialNode* poly1_head = NULL, *poly2_head = NULL, *result_head = NULL;

    // 示例多项式，用户可以根据需要添加更多项
    addTerm(&poly1_head, 1, 2); // x^2
    addTerm(&poly1_head, 5, 1); // 5x

    addTerm(&poly2_head, 4, 0); // 4
    addTerm(&poly2_head, 7, 1); // 7x

    mergePolynomials(&poly1_head, &poly2_head, &result_head);

    printf("Product of two polynomials:\n");
    PolynomialNode* curr = result_head;
    while (curr != NULL) {
        printf("%d*x^%d ", curr->coef, curr->exp);
        curr = curr->next;
    }

    return 0;
}