#define _CRT_SECURE_NO_WARNINGS

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

typedef struct {
    char name[100];
} element;

typedef struct ListNode {
    element data;
    struct ListNode* link;
} ListNode;

element delete_first(ListNode* head) {
    ListNode* removed;
    element data;

    if (head == (ListNode*)NULL)
        return;
    removed = head->link;
    data = removed->data;
    if (head == removed)
        head = NULL;
    else
        head->link = removed->link;
    free(removed);
    return data;
}

ListNode* insert_last(ListNode* head, element data) {
    ListNode* node = (ListNode*)malloc(sizeof(ListNode));
    node->data = data;
    if (head == NULL) {
        head = node;
        node->link = head;
    }
    else {
        node->link = head->link;
        head->link = node;
        head = node;
    }
    return head;
}

// ¸®½ºÆ®ÀÇ Ç׸ñ Ãâ·Â
void print_list(ListNode* head)
{
    ListNode* p;

    if (head == NULL) return;       // µ¥ÀÌÅÍ°¡ ¾øÀ» ¶§
    if (head == head->link) {       // µ¥ÀÌÅÍ°¡ 1°³ ÀÏ ¶§
        printf("%s->\n", head->data);
    }
    else {                          // µ¥ÀÌÅÍ°¡ 2°³ ÀÌ»óÀÏ ¶§
        p = head->link;
        do {
            printf("%s->", p->data);
            p = p->link;
        } while (p != head);
        printf("%s->\n", p->data); // ¸¶Áö¸· ³ëµå Ãâ·Â
    }
}

int main(void) {
    ListNode* head = NULL;
    element data;

    strcpy(data.name, "KIM");
    head = insert_last(head, data);
    print_list(head);

    strcpy(data.name, "PARK");
    head = insert_last(head, data);
    print_list(head);

    strcpy(data.name, "CHOI");
    head = insert_last(head, data);
    print_list(head);

    data = delete_first(head);
    printf("%s\n", data.name);
    data = delete_first(head);
    printf("%s\n", data.name);
    data = delete_first(head);
    printf("%s\n", data.name);

    return 0;
}