Queue.cpp

#include <iostream>
#include <list>
#include <memory>
using namespace std;
template <class T> class Queue {
private:
  unique_ptr<list<T>> data;

public:
  Queue() { data = make_unique<list<T>>(); }
  void enque(T elem) { data->push_back(elem); }
  T &back() { return data->back(); }
  T &front() { return data->front(); }
  void deque() { data->pop_front(); }
  size_t size() { return data->size(); }
  bool empty() { return data->empty(); }
};

int main() {
  Queue<int> queue;
  queue.enque(10);
  queue.enque(20);
  queue.enque(30);
  cout << "Front: " << queue.front() << '\n';
  cout << "Back: " << queue.back() << '\n';
  cout << "Size: " << queue.size() << '\n';
  queue.deque();
  cout << "Front: " << queue.front() << '\n';
  cout << "Back: " << queue.back() << '\n';
  cout << "Size: " << queue.size() << '\n';
  return 0;
}