用c++写双向循环链表

以下是用C++实现双向循环链表的代码：

#include <iostream>

using namespace std;

// 双向循环链表节点结构体
struct Node {
    int data;
    Node *prev;
    Node *next;
};

class DoubleLinkedList {
private:
    Node *head; // 头节点
    Node *tail; // 尾节点
    int size;   // 链表长度

public:
    DoubleLinkedList() {
        head = nullptr;
        tail = nullptr;
        size = 0;
    }

    // 在链表末尾添加节点
    void addNode(int data) {
        Node *newNode = new Node();
        newNode->data = data;
        newNode->prev = tail;
        newNode->next = head;

        if (size == 0) {
            head = newNode;
            tail = newNode;
        } else {
            tail->next = newNode;
            head->prev = newNode;
            tail = newNode;
        }

        size++;
    }

    // 在指定位置插入节点
    void insertNode(int index, int data) {
        if (index < 0 || index > size) {
            cout << "Invalid index" << endl;
            return;
        }

        if (index == 0) {
            addNode(data);
            return;
        }

        if (index == size) {
            Node *newNode = new Node();
            newNode->data = data;
            newNode->prev = tail;
            newNode->next = head;
            tail->next = newNode;
            head->prev = newNode;
            tail = newNode;
            size++;
            return;
        }

        Node *cur = head;
        for (int i = 0; i < index; i++) {
            cur = cur->next;
        }
        Node *newNode = new Node();
        newNode->data = data;
        newNode->prev = cur->prev;
        newNode->next = cur;
        cur->prev->next = newNode;
        cur->prev = newNode;
        size++;
    }

    // 删除指定位置的节点
    void deleteNode(int index) {
        if (index < 0 || index >= size) {
            cout << "Invalid index" << endl;
            return;
        }

        if (index == 0) {
            head = head->next;
            tail->next = head;
            head->prev = tail;
            size--;
            return;
        }

        if (index == size - 1) {
            tail = tail->prev;
            tail->next = head;
            head->prev = tail;
            size--;
            return;
        }

        Node *cur = head;
        for (int i = 0; i < index; i++) {
            cur = cur->next;
        }
        cur->prev->next = cur->next;
        cur->next->prev = cur->prev;
        size--;
    }

    // 获取指定位置的节点值
    int get(int index) {
        if (index < 0 || index >= size) {
            cout << "Invalid index" << endl;
            return -1;
        }

        Node *cur = head;
        for (int i = 0; i < index; i++) {
            cur = cur->next;
        }
        return cur->data;
    }

    // 获取链表长度
    int getSize() {
        return size;
    }

    // 打印链表
    void printList() {
        if (size == 0) {
            cout << "Empty list" << endl;
            return;
        }

        Node *cur = head;
        for (int i = 0; i < size; i++) {
            cout << cur->data << " ";
            cur = cur->next;
        }
        cout << endl;
    }
};

int main() {
    DoubleLinkedList list;
    list.addNode(1);
    list.addNode(2);
    list.addNode(3);
    list.addNode(4);
    list.printList();    // Output: 1 2 3 4
    list.insertNode(2, 5);
    list.printList();    // Output: 1 2 5 3 4
    list.deleteNode(3);
    list.printList();    // Output: 1 2 5 4
    cout << "Size: " << list.getSize() << endl;    // Output: Size: 4
    cout << "Value at index 2: " << list.get(2) << endl;    // Output: Value at index 2: 5
    return 0;
}