#include <stdio.h>
#include <stdlib.h>

typedef struct Node {
    int data;
    struct Node *next;
}Node, *LinkedList;

LinkedList insert(LinkedList head, Node *node, int index) {
    if (head == NULL) {
        if (index != 0) {
            return head;
        }
        head = node;
        head->next = head;
    }
    //head在这里其实已经不能称之为头结点,尾结点应该更合适一些
    if (index == 0) {
        node->next = head->next;
        head->next = node;
        return head;
    }
    Node *current_node = head->next;
    int count = 0;
    //在循环列表中所有结点的下一个结点是不可能为空的,所有循环条件得进行变更
    while (current_node != head && count < count - 1) {
        current_node = current_node->next;
        count++;
    }
    if (count == index - 1) {
        node->next = current_node->next;
        current_node->next = node;
    }
    //如果这个结点插入的位置正好是尾结点的后一个位置,那么要对尾结点进行更新
    if (node == head->next) {
       head = node;
    }

    return head;
}
//删除结点
LinkedList delete_node(LinkedList head, int index) {
    if (head == NULL) {
        return head;
    }
    //删除头结点
    if (index == 0) {
        Node *delete_node = head->next;
        head->next = delete_node->next;
        free(delete_node);
        return head;
    }
    Node *current_node = head->next;
    int count = 0;

    while (current_node != head && count < index - 1) {
        current_node = current_node->next;
        count++;
    }
    if (count == index - 1) {
        Node *delete_node = current_node->next;
        current_node->next = delete_node->next;
        free(delete_node);
    }

    return head;

}
//循环列表反转
LinkedList reverse(LinkedList head) {
    if (head == NULL) {
        return head;
    }
    Node *current_node, *next_node, *top_node;
    current_node = head->next->next;
    head->next->next = head;
    top_node = head->next;
    while (current_node != top_node) {
        next_node = current_node->next;
        current_node->next = head->next;
        head->next = current_node;
        current_node = next_node;
    }

    return head;
}

int main() {

    return 0;
}