덱

#include <iostream> #include <deque> using namespace std; deque <int> dq; void check_push_val(string str, int num) { if (str == "push_front") dq.push_front(num); else if (str == "push_back") dq.push_back(num); } void check_val(string str) { if (str == "pop_front") { if (dq.empty()) cout << -1 << '\n'; else { cout << dq.front() << '\n'; dq.pop_front(); } } else if (str == "pop_back") { if (dq.empty()) cout << -1 << '\n'; else { cout << dq.back() << '\n'; dq.pop_back(); } } else if (str == "size") cout << dq.size() << '\n'; else if (str == "empty") { if (dq.empty()) cout << 1 << '\n'; else cout << 0 << '\n'; } else if (str == "front") { if (dq.empty()) cout << -1 << '\n'; else cout << dq.front() << '\n'; } else if (str == "back") { if (dq.empty()) cout << -1 << '\n'; else cout << dq.back() << '\n'; } } int main() { int n; string str; int num; int result; scanf("%d" , &n); for (int i = 0; i < n; i++) { cin >> str; if (str[1] == 'u') { cin >> num; check_push_val(str, num); } else check_val(str); } return 0; }