큐

FIFO.

프린터처럼 먼저 들어간 종이가 먼저 나옴.

--

배열로 구현

#include <cstdio>
int main()
{
    int num[100], count = 0;
    char command;
    int comnum;
    while (1)
    {
        printf("입력 - i / 삭제 - d\n : ");
        scanf("%c", &command);
        if (command == 'i')
        {
            printf("입력할 자연수 : ");
            scanf("%d", &comnum);
            num[count++] = comnum;
        }
        else if (command == 'd' && count > 0)
            printf("%d\n", num[--count]);
        while (getchar() != '\n');
    }
}

--

연결리스트로 구현

#include <cstdio>
struct node 
{
    node *next;
    node *prev;
    int data;
};
 
node *head, *foot;
 
void init();
 
int main()
{
    init();
    node *newnode;
    char command;
    int comnum, count = 0;
    while (1)
    {
        printf("입력 - i / 삭제 - d\n : ");
        scanf("%c", &command);
        if (command == 'i')
        {
            printf("입력할 자연수 : ");
            scanf("%d", &comnum);
            newnode = new node;
            newnode->next = head->next;
            newnode->prev = head;
            newnode->next->prev = head->next = newnode;
            newnode->data = comnum;
            ++count;
        }
        else if (command == 'd' && count > 0)
        {
            newnode = foot->prev;
            foot->prev = newnode->prev;
            newnode->prev->next = foot;
            printf("%d\n", newnode->data);
            --count;
            delete newnode;
        }
        while (getchar() != '\n');
    }
}
 
void init()
{
    head = new node;
    foot = new node;
    head->next = foot->next = foot;
    head->prev = foot->prev = head;
    head->data = foot->data = -1;
}