[백준] 10845번 : 큐 - C

https://www.acmicpc.net/problem/10845

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

struct Queue{
    int queue[10001];
    int first;
    int last;
}t;

void push(int num) {
	t.queue[t.last] = num;
	t.last++;
}
void pop() {
	if(t.last-t.first == 0) printf("-1\n");
	else {
	    int ans = t.queue[t.first];
		t.queue[t.first] = 0;
		t.first++;
		printf("%d\n",ans);
	}
}
void size() {
	printf("%d\n",t.last-t.first);
}
void empty() {
	if(t.last-t.first == 0) printf("1\n");
	else printf("0\n");
}
static void front() {
	if(t.last-t.first == 0) printf("-1\n");
	else printf("%d\n",t.queue[t.first]);
}
static void back() {
	if(t.last-t.first == 0) printf("-1\n");
	else printf("%d\n",t.queue[t.last - 1]);
}

int main() {
    t.first=0;
    t.last=0;
    
    int n;
    scanf("%d",&n);
    
    for(int i=0;i<n;i++){
        char st[10];
        scanf("%s",&st);
        if (strcmp(st, "push")==0) {
            int num;
			scanf("%d", &num);
			push(num);
		}
		else if(strcmp(st, "pop")==0) {
			pop();
		}
		else if(strcmp(st, "size")==0) {
			size();
		}
		else if(strcmp(st, "empty")==0) {
			empty();
		}
		else if(strcmp(st, "front")==0) {
			front();
		}
		else if(strcmp(st, "back")==0) {
			back();
		}
    }
}