#include <iostream>
#include <vector>
#include <memory>

using namespace std;

class Animal {
 public:
  Animal(const string& type) : type_(type) {}

  void Eat(const string& fruit) {
    cout << type_ << " eats " << fruit << endl;
  }

  virtual void Sound() const = 0;

 private:
  const string type_;
};


class Cat : public Animal {
 public:
  Cat() : Animal("cat") {}

  void Sound() const override {
    cout << "Meow!" << endl;
  }
};


class Dog : public Animal {
 public:
  Dog() : Animal("dog") {}

  void Sound() const override {
    cout << "Whaf!" << endl;
  }
};


class Parrot : public Animal {
 public:
  Parrot(const string& name) : Animal("parrot"), name_(name) {}

  void Sound() const override {
    cout << name_ << " is good!" << endl;
  }

 private:
  const string& name_;
};


class Horse : public Animal {
 public:
  Horse() : Animal("horse") {}

  void Sound() const override {
    cout << "some sound" << endl;
  }
};


void MakeSound(const Animal& a) {
  a.Sound();
}

int main() {
  vector<shared_ptr<Animal>> animals{
      make_shared<Cat>(),
      make_shared<Dog>(),
      make_shared<Parrot>("Kesha"),
      make_shared<Horse>(),
  };

  for (auto a : animals) {
    MakeSound(*a);
  }

  return 0;
}