为一个不定长多维数字信号设计一个链表，并实现对其进行基本操作，包括初始化、求 数据元素个数操作、插入、删除、取数据元素、判非空 ，均值滤波、上采样和下采样

链表节点定义如下：

typedef struct node {
    double data;
    struct node *next;
} Node;

链表操作函数定义如下：

/**
 * 初始化链表
 * @param head 链表头
 */
void initList(Node *&head) {
    head = new Node;
    head->next = nullptr;
}

/**
 * 求链表长度
 * @param head 链表头
 * @return 链表长度
 */
int getListLength(Node *head) {
    int len = 0;
    Node *p = head->next;
    while (p != nullptr) {
        len++;
        p = p->next;
    }
    return len;
}

/**
 * 插入数据元素
 * @param head 链表头
 * @param data 要插入的数据元素
 * @param pos 插入位置
 * @return 插入是否成功
 */
bool insertList(Node *&head, double data, int pos) {
    int len = getListLength(head);
    if (pos < 1 || pos > len + 1) {
        return false;
    }

    Node *p = head;
    for (int i = 1; i < pos; i++) {
        p = p->next;
    }

    Node *newNode = new Node;
    newNode->data = data;
    newNode->next = p->next;
    p->next = newNode;

    return true;
}

/**
 * 删除数据元素
 * @param head 链表头
 * @param pos 删除位置
 * @return 删除是否成功
 */
bool deleteList(Node *&head, int pos) {
    int len = getListLength(head);
    if (pos < 1 || pos > len) {
        return false;
    }

    Node *p = head;
    for (int i = 1; i < pos; i++) {
        p = p->next;
    }

    Node *q = p->next;
    p->next = q->next;
    delete q;

    return true;
}

/**
 * 取数据元素
 * @param head 链表头
 * @param pos 取出位置
 * @param data 取出的数据元素
 * @return 取出是否成功
 */
bool getData(Node *head, int pos, double &data) {
    int len = getListLength(head);
    if (pos < 1 || pos > len) {
        return false;
    }

    Node *p = head->next;
    for (int i = 1; i < pos; i++) {
        p = p->next;
    }

    data = p->data;
    return true;
}

/**
 * 判断链表是否为空
 * @param head 链表头
 * @return 是否为空
 */
bool isListEmpty(Node *head) {
    return head->next == nullptr;
}

/**
 * 均值滤波
 * @param head 链表头
 * @param window 窗口大小
 * @return 滤波后的链表头
 */
Node *meanFilter(Node *head, int window) {
    Node *newHead;
    initList(newHead);

    int len = getListLength(head);
    if (window > len) {
        window = len;
    }

    for (int i = 1; i <= len; i++) {
        double sum = 0;
        int count = 0;
        for (int j = i - window / 2; j <= i + window / 2; j++) {
            double data;
            if (getData(head, j, data)) {
                sum += data;
                count++;
            }
        }
        double mean = sum / count;
        insertList(newHead, mean, i);
    }

    return newHead;
}

/**
 * 上采样
 * @param head 链表头
 * @param factor 上采样因子
 * @return 上采样后的链表头
 */
Node *upSample(Node *head, int factor) {
    Node *newHead;
    initList(newHead);

    int len = getListLength(head);
    for (int i = 1; i <= len; i++) {
        double data;
        if (getData(head, i, data)) {
            insertList(newHead, data, i);
            for (int j = 2; j <= factor; j++) {
                insertList(newHead, data, i + (j - 1) * len);
            }
        }
    }

    return newHead;
}

/**
 * 下采样
 * @param head 链表头
 * @param factor 下采样因子
 * @return 下采样后的链表头
 */
Node *downSample(Node *head, int factor) {
    Node *newHead;
    initList(newHead);

    int len = getListLength(head);
    for (int i = 1; i <= len; i += factor) {
        double data;
        if (getData(head, i, data)) {
            insertList(newHead, data, getListLength(newHead) + 1);
        }
    }

    return newHead;
}