c语言链表实现多项式加减

C语言链表可以用来实现多项式的加减运算。下面是一种常见的链表结构来表示多项式：

// 定义多项式的节点结构
typedef struct Node {
    int coefficient;  // 系数
    int exponent;     // 指数
    struct Node* next;  // 指向下一个节点的指针
} Node;

// 多项式相加函数
Node* addPolynomials(Node* poly1, Node* poly2) {
    Node* result = NULL;  // 存储结果的链表头节点
    Node* tail = NULL;    // 存储结果的链表尾节点

    while (poly1 != NULL && poly2 != NULL) {
        Node* newNode = (Node*)malloc(sizeof(Node));
        newNode->next = NULL;

        if (poly1->exponent > poly2->exponent) {
            newNode->coefficient = poly1->coefficient;
            newNode->exponent = poly1->exponent;
            poly1 = poly1->next;
        } else if (poly1->exponent < poly2->exponent) {
            newNode->coefficient = poly2->coefficient;
            newNode->exponent = poly2->exponent;
            poly2 = poly2->next;
        } else {
            newNode->coefficient = poly1->coefficient + poly2->coefficient;
            newNode->exponent = poly1->exponent;
            poly1 = poly1->next;
            poly2 = poly2->next;
        }

        if (result == NULL) {
            result = newNode;
            tail = newNode;
        } else {
            tail->next = newNode;
            tail = newNode;
        }
    }

    // 将剩余的节点添加到结果链表中
    if (poly1 != NULL) {
        tail->next = poly1;
    }
    if (poly2 != NULL) {
        tail->next = poly2;
    }

    return result;
}

// 多项式相减函数
Node* subtractPolynomials(Node* poly1, Node* poly2) {
    Node* result = NULL;  // 存储结果的链表头节点
    Node* tail = NULL;    // 存储结果的链表尾节点

    while (poly1 != NULL && poly2 != NULL) {
        Node* newNode = (Node*)malloc(sizeof(Node));
        newNode->next = NULL;

        if (poly1->exponent > poly2->exponent) {
            newNode->coefficient = poly1->coefficient;
            newNode->exponent = poly1->exponent;
            poly1 = poly1->next;
        } else if (poly1->exponent < poly2->exponent) {
            newNode->coefficient = -poly2->coefficient;
            newNode->exponent = poly2->exponent;
            poly2 = poly2->next;
        } else {
            newNode->coefficient = poly1->coefficient - poly2->coefficient;
            newNode->exponent = poly1->exponent;
            poly1 = poly1->next;
            poly2 = poly2->next;
        }

        if (result == NULL) {
            result = newNode;
            tail = newNode;
        } else {
            tail->next = newNode;
            tail = newNode;
        }
    }

    // 将剩余的节点添加到结果链表中
    if (poly1 != NULL) {
        tail->next = poly1;
    }
    if (poly2 != NULL) {
        tail->next = poly2;
    }

    return result;
}

上述代码中，我们定义了一个多项式的节点结构，包含系数和指数，并且有一个指向下一个节点的指针。`addPolynomials`函数用于实现多项式的加法，`subtractPolynomials`函数用于实现多项式的减法。这两个函数都接受两个多项式的链表作为输入，并返回一个新的链表作为结果。