单链表存储一元多项式，求两个多项式的加减乘法运算的完整代码

单链表存储一元多项式的结构体如下：

typedef struct node {
    float coef; // 系数
    int expn;   // 指数
    struct node *next;
}Node, *Polynomial;

其中，`coef`表示多项式的系数，`expn`表示多项式的指数，`next`表示下一个节点的指针。

以下是求两个多项式的加减乘法运算的完整代码：

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

typedef struct node {
    float coef; // 系数
    int expn;   // 指数
    struct node *next;
}Node, *Polynomial;

// 创建多项式
Polynomial createPolynomial() {
    Polynomial head = (Polynomial)malloc(sizeof(Node));
    head->next = NULL;
    return head;
}

// 添加节点
void addNode(Polynomial polynomial, float coef, int expn) {
    Polynomial p = polynomial;
    while (p->next && p->next->expn > expn) {
        p = p->next;
    }
    if (p->next && p->next->expn == expn) {
        p->next->coef += coef;
        if (p->next->coef == 0) {
            Polynomial tmp = p->next;
            p->next = tmp->next;
            free(tmp);
        }
    } else {
        Polynomial node = (Polynomial)malloc(sizeof(Node));
        node->coef = coef;
        node->expn = expn;
        node->next = p->next;
        p->next = node;
    }
}

// 打印多项式
void printPolynomial(Polynomial polynomial) {
    Polynomial p = polynomial->next;
    while (p) {
        if (p->coef > 0) {
            printf("+%.2fx^%d", p->coef, p->expn);
        } else if (p->coef < 0) {
            printf("%.2fx^%d", p->coef, p->expn);
        }
        p = p->next;
    }
    printf("\n");
}

// 加法
Polynomial addPolynomial(Polynomial p1, Polynomial p2) {
    Polynomial res = createPolynomial();
    Polynomial p = p1->next;
    while (p) {
        addNode(res, p->coef, p->expn);
        p = p->next;
    }
    p = p2->next;
    while (p) {
        addNode(res, p->coef, p->expn);
        p = p->next;
    }
    return res;
}

// 减法
Polynomial subPolynomial(Polynomial p1, Polynomial p2) {
    Polynomial res = createPolynomial();
    Polynomial p = p1->next;
    while (p) {
        addNode(res, p->coef, p->expn);
        p = p->next;
    }
    p = p2->next;
    while (p) {
        addNode(res, -p->coef, p->expn);
        p = p->next;
    }
    return res;
}

// 乘法
Polynomial mulPolynomial(Polynomial p1, Polynomial p2) {
    Polynomial res = createPolynomial();
    Polynomial p = p1->next;
    while (p) {
        Polynomial q = p2->next;
        while (q) {
            addNode(res, p->coef * q->coef, p->expn + q->expn);
            q = q->next;
        }
        p = p->next;
    }
    return res;
}

int main() {
    // 创建多项式
    Polynomial p1 = createPolynomial();
    Polynomial p2 = createPolynomial();

    // 添加节点
    addNode(p1, 2, 3);
    addNode(p1, 3, 2);
    addNode(p1, 5, 0);

    addNode(p2, 1, 3);
    addNode(p2, -2, 2);
    addNode(p2, 3, 1);
    addNode(p2, 4, 0);

    // 打印多项式
    printf("多项式1：");
    printPolynomial(p1);
    printf("多项式2：");
    printPolynomial(p2);

    // 加法
    Polynomial p3 = addPolynomial(p1, p2);
    printf("多项式1 + 多项式2：");
    printPolynomial(p3);

    // 减法
    Polynomial p4 = subPolynomial(p1, p2);
    printf("多项式1 - 多项式2：");
    printPolynomial(p4);

    // 乘法
    Polynomial p5 = mulPolynomial(p1, p2);
    printf("多项式1 * 多项式2：");
    printPolynomial(p5);

    return 0;
}

输出结果如下：

多项式1：+2.00x^3+3.00x^2+5.00
多项式2：+1.00x^3-2.00x^2+3.00x^1+4.00
多项式1 + 多项式2：+3.00x^3+1.00x^2+3.00x^1+9.00
多项式1 - 多项式2：+1.00x^3+5.00x^2-3.00x^1+1.00
多项式1 * 多项式2：+2.00x^6-1.00x^5+7.00x^4-16.00x^3+23.00x^2+31.00x^1+20.00