利用链表实现多项式加法运算，并计算多项式p1(x)和p2(x)相加的结果。 p1(x) = 7+3x+9x^8+5x^17, p2(x) = 8x+22x^7-9x^8

要使用链表实现多项式加法运算，我们可以创建一个节点结构，每个节点包含系数和指数。对于给定的两个多项式p1(x)和p2(x)，我们需要遍历两个链表，分别对应p1和p2的每一项，然后根据指数相加规则（相同指数项相加）更新节点的系数。

首先，定义一个节点结构`Node`：

typedef struct {
    int coefficient;
    int exponent; // 或者用long long避免溢出
    struct Node* next;
} PolynomialTerm;

接下来，创建两个链表表示p1和p2：

PolynomialTerm* p1_head = NULL;
PolynomialTerm* p2_head = NULL;

// 初始化p1链表，添加每一项
PolynomialTerm* p1_current = malloc(sizeof(PolynomialTerm));
p1_current->coefficient = 7;
p1_current->exponent = 0;
p1_current->next = NULL;
if (p1_head == NULL) {
    p1_head = p1_current;
}

// 添加p2链表，同样初始化每一项
PolynomialTerm* p2_current = malloc(sizeof(PolynomialTerm));
p2_current->coefficient = 8;
p2_current->exponent = 1;
p2_current->next = NULL;
if (p2_head == NULL) {
    p2_head = p2_current;
}
// 假设还有其他p2的项，按照同样的方式添加

// 进行加法操作
PolynomialTerm* result_head = NULL;
PolynomialTerm* result_current = NULL;
for (PolynomialTerm* current = p1_head; current != NULL; current = current->next) {
    for (PolynomialTerm* other = p2_head; other != NULL; other = other->next) {
        if (current->exponent == other->exponent) {
            // 同一项，合并系数
            current->coefficient += other->coefficient;
            // 如果合并后系数为0，说明不需要保留该项
            if (current->coefficient == 0) {
                free(current);
                current = NULL;
            } else {
                break;
            }
        } else if (current->exponent < other->exponent) {
            // 结果链表上没有相同或更小指数的项，插入当前项
            if (result_head == NULL) {
                result_head = current;
                result_current = current;
            } else {
                result_current->next = current;
                result_current = current;
            }
        }
    }
    // 如果p1还没有处理完，将其剩余项添加到结果链表
    if (current != NULL) {
        result_head = current;
        result_current = current;
    }
}

// 清理p2链表（如果不需要）
free(p2_current);
while (p2_head != NULL) {
    PolynomialTerm* temp = p2_head;
    p2_head = p2_head->next;
    free(temp);
}

return result_head;