백준 알고리즘 10845번 큐

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX 10000
 
typedef struct {
    int max;
    int num;
    int rear;
    int front;
    int *que;
}Queue;
 
int Initialize(Queue *q, int max) {
    q->num = q->front = q->rear = 0;
    if ((q->que = (int*)calloc(max, sizeof(int))) == NULL) {
        q->max = 0;
        return -1;
    }
    q->max = max;
    return 0;
}
 
int Enque(Queue *q, int x) {
    if (q->num >= q->max)
        return -1;
    else {
        q->num++;
        q->que[q->rear++] = x;
        if (q->rear == q->max)
            q->rear = 0;
        return 0;
    }
}
 
void Deque(Queue *q, int *x) {
    if (q->num <= 0)
        printf("%d\n", -1);
    else {
        q->num--;
        *x = q->que[q->front++];
        if (q->front == q->max)
            q->front = 0;
        printf("%d\n", *x);
    }
}
 
void back(Queue *q) {
    if (q->num <= 0)
        printf("%d\n", -1);
    else
        printf("%d\n", q->que[q->rear-1]);
}
 
void front(Queue *q) {
    if (q->num <= 0)
        printf("%d\n", -1);
    else
        printf("%d\n", q->que[q->front]);
}
 
void size(Queue *q) {
    printf("%d\n", q->num);
}
 
void IsEmpty(Queue *q) {
    if (q->num <= 0)
        printf("%d\n", 1);
    else
        printf("%d\n", 0);
}
 
int IsFull(Queue *q) {
    return q->num >= q->max;
}
 
int main() {
    Queue q;
    int ans = 0, input = 0;
    char ans1[] = "empty";
    ans1[0] = '\0';
 
    Initialize(&q, MAX);
    scanf("%d", &ans);
 
    while (ans > 0) {
        scanf("%s", ans1);
 
        if (strcmp(ans1, "push") == 0) {
            scanf("%d", &input);
            Enque(&q, input);
        }
        else if (strcmp(ans1, "pop") == 0)
            Deque(&q, &input);
 
        else if (strcmp(ans1, "size") == 0)
            size(&q);
 
        else if (strcmp(ans1, "empty") == 0)
            IsEmpty(&q);
 
        else if (strcmp(ans1, "front") == 0)
            front(&q);
 
        else if (strcmp(ans1, "back") == 0)
            back(&q);
 
        ans--;
    }
    return 0;
}