큐

#include <iostream> #include <queue> #include <string> int N; std::string s; std::queue<int> que; std::vector<int> result; // push, pop, size, empty, front, back void output() { for (auto &i : result) std::cout << i << '\n'; } void solution() { int num; if (s == "push") { std::cin >> num; que.push(num); } else if (s == "pop") { if(que.empty()) { result.push_back(-1); } else { result.push_back(que.front()); que.pop(); } } else if (s == "size") result.push_back(que.size()); else if (s == "empty") { if (que.empty()) result.push_back(1); else result.push_back(0); } else if (s == "front") { if (que.empty()) result.push_back(-1); else result.push_back(que.front()); } else { if (que.empty()) result.push_back(-1); else result.push_back(que.back()); } } void input() { std::cin >> N; for (int i = 0; i < N; ++i) { std::cin >> s; solution(); } } void preset() { std::ios_base::sync_with_stdio(false); std::cin.tie(NULL); std::cout.tie(NULL); } int main() { preset(); input(); output(); }