建立一元多项式单链表时，根据输入值来确定结束构建单链表， 编写一元多项式的相加程序，要编写多项式单链表的输出函数，以便能验证程序的执行结果的C语言代码和注释

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

typedef struct node {
    float coef; // 系数
    int expn; // 指数
    struct node *next; // 指向下一个节点的指针
} Node, *Polynomial;

// 创建多项式单链表
void createPoly(Polynomial *p) {
    *p = NULL; // 初始化为空链表
    Node *tail = *p; // 定义尾指针
    float c; // 系数
    int e; // 指数
    printf("请输入多项式的系数和指数（以0 0结束）：\n");
    while (1) {
        scanf("%f%d", &c, &e);
        if (c == 0 && e == 0) {
            break; // 输入0 0时结束
        }
        Node *newNode = (Node *)malloc(sizeof(Node)); // 动态分配一个新节点
        newNode->coef = c;
        newNode->expn = e;
        newNode->next = NULL;
        if (*p == NULL) {
            *p = newNode; // 第一个节点
        } else {
            tail->next = newNode;
        }
        tail = newNode; // 将尾指针指向新节点
    }
}

// 输出多项式单链表
void printPoly(Polynomial p) {
    if (p == NULL) {
        printf("多项式为空！\n");
    } else {
        printf("多项式为：");
        while (p != NULL) {
            if (p->expn == 0) {
                printf("%.1f", p->coef);
            } else if (p->expn == 1) {
                printf("%.1fx", p->coef);
            } else {
                printf("%.1fx^%d", p->coef, p->expn);
            }
            p = p->next;
            if (p != NULL) {
                printf(" + ");
            }
        }
        printf("\n");
    }
}

// 多项式相加
Polynomial addPoly(Polynomial p1, Polynomial p2) {
    Node *tail; // 新链表尾指针
    Node *temp; // 临时节点指针
    Polynomial p3 = NULL; // 新链表头指针
    tail = p3;
    while (p1 != NULL && p2 != NULL) {
        if (p1->expn == p2->expn) { // 指数相同
            float sum = p1->coef + p2->coef;
            if (sum != 0) { // 系数和不为0
                Node *newNode = (Node *)malloc(sizeof(Node));
                newNode->coef = sum;
                newNode->expn = p1->expn;
                newNode->next = NULL;
                if (p3 == NULL) {
                    p3 = newNode;
                } else {
                    tail->next = newNode;
                }
                tail = newNode;
            }
            p1 = p1->next;
            p2 = p2->next;
        } else if (p1->expn > p2->expn) { // p1的指数大于p2的指数
            Node *newNode = (Node *)malloc(sizeof(Node));
            newNode->coef = p1->coef;
            newNode->expn = p1->expn;
            newNode->next = NULL;
            if (p3 == NULL) {
                p3 = newNode;
            } else {
                tail->next = newNode;
            }
            tail = newNode;
            p1 = p1->next;
        } else { // p2的指数大于p1的指数
            Node *newNode = (Node *)malloc(sizeof(Node));
            newNode->coef = p2->coef;
            newNode->expn = p2->expn;
            newNode->next = NULL;
            if (p3 == NULL) {
                p3 = newNode;
            } else {
                tail->next = newNode;
            }
            tail = newNode;
            p2 = p2->next;
        }
    }
    // 将剩余的节点加入新链表
    if (p1 != NULL) {
        temp = p1;
    } else {
        temp = p2;
    }
    while (temp != NULL) {
        Node *newNode = (Node *)malloc(sizeof(Node));
        newNode->coef = temp->coef;
        newNode->expn = temp->expn;
        newNode->next = NULL;
        if (p3 == NULL) {
            p3 = newNode;
        } else {
            tail->next = newNode;
        }
        tail = newNode;
        temp = temp->next;
    }
    return p3;
}

int main() {
    Polynomial p1, p2, p3;
    printf("请输入第一个多项式：\n");
    createPoly(&p1);
    printPoly(p1);
    printf("请输入第二个多项式：\n");
    createPoly(&p2);
    printPoly(p2);
    p3 = addPoly(p1, p2);
    printf("两个多项式相加的结果为：\n");
    printPoly(p3);
    return 0;
}