[백준] 10845: 큐

10845번: 큐

#include <iostream>
#include <string>

template<typename T>
struct Queue {
	T data[10000];
	int begin, end;
	
	Queue() : begin(0), end(0) {}
	
	void push(int num) {
		if (empty()) {
			data[begin] = num;
			end++;
		}
		else {
			data[end++] = num;
		}
	}
	
	int pop() { 
		if (empty()) { return -1; }
		return data[begin++];
	}

	int size() { 
		return end - begin;
	}

	bool empty() { 
		if (begin == end) { return true; }
		return false;
	}

	int front() {
		if (empty()) { return -1; }
		return data[begin];
	}

	int back() {
		if (empty()) { return -1; }
		return data[end-1]; 
	}
};

int main() {
	using namespace std; ios_base::sync_with_stdio(false);
	cin.tie(nullptr); cout.tie(nullptr);

	Queue<int> que;
	int t; cin >> t;
	while (t--) {
		string cmd; cin >> cmd;
		if (cmd == "push") {
			int num; cin >> num;
			que.push(num);
		}
		else if (cmd == "pop") {
			cout << que.pop() << "\n";
		}
		else if (cmd == "size") {
			cout << que.size() << "\n";
		}
		else if (cmd == "empty") {
			cout << que.empty() << "\n";
		}
		else if (cmd == "front") {
			cout << que.front() << "\n";
		}
		else if (cmd == "back") {
			cout << que.back() << "\n";
		}
		else if (cmd == "break") { break; }
	}
}