C++ 环形双向链表删除操作：高效实现与优化

#include <iostream>
using namespace std;

struct Node {
    int data;
    Node *prev, *next;
};

// 创建一个新的节点
Node* newNode(int data) {
    Node* node = new Node;
    node->data = data;
    node->prev = node->next = node;
    return node;
}

// 在链表中插入一个节点
void insert(Node** head, int data) {
    if (*head == NULL) {
        *head = newNode(data);
        return;
    }

    Node* new_node = newNode(data);
    new_node->next = *head;
    new_node->prev = (*head)->prev;
    (*head)->prev->next = new_node;
    (*head)->prev = new_node;
}

// 删除链表中的节点
void deleteNode(Node** head, int data) {
    if (*head == NULL) {
        return;
    }

    Node* current = *head;
    bool found = false;
    do {
        if (current->data == data) {
            found = true;
            // 如果是最后一个节点
            if (current->next == current) {
                *head = NULL;
            } else {
                current->prev->next = current->next;
                current->next->prev = current->prev;
                if (*head == current) {
                    *head = current->next;
                }
            }
            delete current;
            current = *head; // 重置 current 为头节点，继续遍历
        } else {
            current = current->next;
        }
    } while (current != *head);

    if (!found) {
        cout << -1 << endl;
    }
}

// 打印链表
void printList(Node* head) {
    if (head == NULL) {
        return;
    }
    Node* current = head;
    do {
        cout << current->data << ' ';
        current = current->next;
    } while (current != head);
    cout << endl;
}

int main() {
    Node* head = NULL;
    int data;
    cin >> data;
    while (data != -1) {
        insert(&head, data);
        cin >> data;
    }

    cin >> data;
    while (data != -1) {
        deleteNode(&head, data);
        printList(head);
        cin >> data;
    }

    printList(head);
    return 0;
}