[BOJ] 10845 큐 / C++

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

10845번: 큐

 

#include <iostream>
#include <string>
#define MAX_CAPACITY	10000

using namespace std;

int N; // 명령의 수 (1<= <= 10000)
int queue[MAX_CAPACITY] = { 0, };
int front_ptr = 0, back_ptr = 0; // queue pointers

string cmd;
int input_data;

void push(int n) {
	if (back_ptr != MAX_CAPACITY) {
		queue[++back_ptr] = n;
	}
}

int pop() {
	if (front_ptr == back_ptr) return -1;
	int num = queue[front_ptr + 1];
	front_ptr++;
	return num;
}

int size() {
	return (back_ptr - front_ptr);
}

int empty() {
	if (front_ptr == back_ptr) return 1;
	else return 0;
}

int front() {
	if (front_ptr == back_ptr) return -1;
	return queue[front_ptr + 1];
}

int back() {
	if (front_ptr == back_ptr) return -1;
	return queue[back_ptr];
}


int main(void)
{
	cin >> N;
	for (int i = 0; i < N; i++) {
		cin >> cmd;
		if (cmd == "push") {
			cin >> input_data;
			push(input_data);
		}
		else if (cmd == "pop") {
			int top_num = pop();
			cout << top_num << "\n";
		}
		else if (cmd == "size") {
			int queue_size = size();
			cout << queue_size << "\n";
		}
		else if (cmd == "empty") {
			int is_empty = empty();
			cout << is_empty << "\n";
		}
		else if (cmd == "front") {
			int num = front();
			cout << num << "\n";
		}
		else if (cmd == "back") {
			int num = back();
			cout << num << "\n";
		}
	}
	return 0;
}