[백준,c++] 10866번 - 덱

10866번: 덱

#include <iostream>
#include <queue>

using namespace std;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    int N; cin >> N;
    deque<int>dq;
    while (N--) {
        string s; cin >> s;
        if (s == "push_back") {
            int num; cin >> num;
            dq.push_back(num);
        }
        else if (s == "push_front") {
            int num; cin >> num;
            dq.push_front(num);
        }
        else if (s == "pop_front") {
            if (dq.empty()) cout << -1 << "\n";
            else {
                cout << dq.front() << "\n";
                dq.pop_front();
            }
        }
        else if (s == "pop_back") {
            if (dq.empty()) cout << -1 << "\n";
            else {
                cout << dq.back() << "\n";
                dq.pop_back();
            }
        }
        else if (s == "size") {
            cout << dq.size() << "\n";
        }
        else if (s == "empty") {
            if (dq.empty())cout << 1 << "\n";
            else cout << 0 << "\n";
        }
        else if (s == "front") {
            if (dq.empty()) cout << -1 << "\n";
            else cout << dq.front() << "\n";
        }
        else if (s == "back") {
            if (dq.empty()) cout << -1 << "\n";
            else cout << dq.back() << "\n";
        }

    }
}