数据结构实现链表基本操作，并用rand函数测试每个函数的运行时间

好的，以下是用C++实现链表基本操作，并用rand函数测试每个函数的运行时间的代码：

#include <iostream>
#include <ctime>
using namespace std;

struct Node {
    int val;
    Node *next;
    Node(int x) : val(x), next(NULL) {}
};

class LinkedList {
public:
    LinkedList() {
        head = NULL;
    }

    void addAtHead(int val) {
        Node *newNode = new Node(val);
        newNode->next = head;
        head = newNode;
    }

    void addAtTail(int val) {
        if (head == NULL) {
            addAtHead(val);
            return;
        }
        Node *cur = head;
        while (cur->next != NULL) {
            cur = cur->next;
        }
        cur->next = new Node(val);
    }

    void addAtIndex(int index, int val) {
        if (index == 0) {
            addAtHead(val);
            return;
        }
        int i = 0;
        Node *cur = head;
        while (cur != NULL && i < index - 1) {
            cur = cur->next;
            i++;
        }
        if (cur == NULL) {
            return;
        }
        Node *newNode = new Node(val);
        newNode->next = cur->next;
        cur->next = newNode;
    }

    void deleteAtIndex(int index) {
        if (head == NULL) {
            return;
        }
        if (index == 0) {
            Node *temp = head;
            head = head->next;
            delete temp;
            return;
        }
        int i = 0;
        Node *cur = head;
        while (cur != NULL && i < index - 1) {
            cur = cur->next;
            i++;
        }
        if (cur == NULL || cur->next == NULL) {
            return;
        }
        Node *temp = cur->next;
        cur->next = cur->next->next;
        delete temp;
    }

    void printList() {
        Node *cur = head;
        while (cur != NULL) {
            cout << cur->val << " ";
            cur = cur->next;
        }
        cout << endl;
    }

private:
    Node *head;
};

int main() {
    LinkedList list;

    srand(time(NULL)); // 初始化rand函数

    // 随机生成1000个数，插入链表并打印链表
    clock_t start = clock();
    for (int i = 0; i < 1000; i++) {
        int val = rand() % 100;
        list.addAtTail(val);
    }
    list.printList();
    clock_t end = clock();
    cout << "Time used: " << end - start << endl;

    // 在第500个位置插入一个数，并打印链表
    start = clock();
    list.addAtIndex(500, 999);
    list.printList();
    end = clock();
    cout << "Time used: " << end - start << endl;

    // 删除第500个数，并打印链表
    start = clock();
    list.deleteAtIndex(500);
    list.printList();
    end = clock();
    cout << "Time used: " << end - start << endl;

    return 0;
}

上面的代码中，我们用rand函数随机生成了1000个数，插入链表中，并打印了链表。然后在第500个位置插入了一个数，并打印了链表。最后删除了第500个数，并打印了链表。每个操作都用clock函数计算了运行时间。

需要注意的是，这里使用了rand函数生成随机数，所以每次运行结果可能会不同。