#include <stdio.h>
#include <stdlib.h>
// 双向链表节点定义
typedef struct Node {
    int data;
    struct Node *prev;
    struct Node *next;
} Node;
// 创建新节点
Node* createNode(int data) {
    Node* newNode = (Node*)malloc(sizeof(Node));
    if (newNode == NULL) {
        printf("Memory allocation failed\n");
        exit(1);
    }
    newNode->data = data;
    newNode->prev = NULL;
    newNode->next = NULL;
    return newNode;
}
// 在链表末尾插入节点
void append(Node** headRef, int data) {
    Node* newNode = createNode(data);
    if (*headRef == NULL) {
        *headRef = newNode;
        return;
    }
    Node* current = *headRef;
    while (current->next != NULL) {
        current = current->next;
    }
    current->next = newNode;
    newNode->prev = current;
}
// 打印链表元素
void printList(Node* head) {
    Node* current = head;
    printf("List: ");
    while (current != NULL) {
        printf("%d ", current->data);
        current = current->next;
    }
    printf("\n");
}
// 反向打印链表元素
void reversePrintList(Node* head) {
    Node* current = head;
    if (current == NULL) {
        return;
    }
    // 移动到链表末尾
    while (current->next != NULL) {
        current = current->next;
    }
    printf("Reverse List: ");
    // 从末尾开始反向遍历并打印元素
    while (current != NULL) {
        printf("%d ", current->data);
        current = current->prev;
    }
    printf("\n");
}
// 释放链表内存
void freeList(Node** headRef) {
    Node* current = *headRef;
    Node* next;
    while (current != NULL) {
        next = current->next;
        free(current);
        current = next;
    }
    *headRef = NULL;
}
int main() {
    Node* head = NULL;
    // 在链表末尾插入元素
    append(&head, 1);
    append(&head, 2);
    append(&head, 3);
    // 打印链表元素
    printList(head);
    // 反向打印链表元素
    reversePrintList(head);
    // 释放链表内存
    freeList(&head);
    return 0;
}