How would you refactore this code, on your ways, for best performance and simplicity.

[Stellow]

Just a topic to discuss the best c++ new approaches for performance and simplicity.
- Note you need a base class animal, and subclasses.

#include <iostream>
#include <string>
#include <vector>
#include <memory>
#include <cassert>
using namespace std;

enum class animals{ fish, insects, reptiles, mammals, amphibians, birds, last};
ostream& operator<<(ostream& os, animals obj)
{
    switch (static_cast<int>(obj))
    {
    case 0: os << "Fishes"; break;
    case 1: os << "Insects"; break;
    case 2: os << "Reptiles"; break;
    case 3: os << "Mammals"; break;
    case 4: os << "Amphibians"; break;
    case 5: os << "Birds"; break;
    default: os << "Unknow";
    }
    return os;
}
class animal
{
public:
    void printAllAnimals() const;
    int returnAnimalCount() const { return animalC; };
    virtual void push_animal(string&&){};
    virtual void print() const{};
protected:
    static int animalC;
    void insert(const animals&, string&&);
    void printAnimalTable(const animals&) const;
private:
    vector<vector<string>> container{static_cast<int>(animals::last)};
};
int animal::animalC = 0;
void animal::insert(const animals& obj, string&& s)
{
    container[static_cast<int>(obj)].push_back(move(s));
    animalC++;
}
void animal::printAnimalTable(const animals& obj) const
{
    cout << obj << ": ";
    for (int i = 0; i < container[static_cast<int>(obj)].size(); i++)
    {
        cout << container[static_cast<int>(obj)][i] << " ";
    }
}
void animal::printAllAnimals() const{
    for (int i = 0; i < container.size(); i++)
    {
        cout << animals(i) << ": ";
        for (int j = 0; j < container[i].size(); j++)
        {
            cout << container[static_cast<int>(i)][j] << " ";
        }
        cout << endl;
    }
}
class fish : public animal
{
public:
    fish() :numFishes(0){};
    void push_animal(string&& s)
    {
        insert(animals::fish, forward<string>(s));
        numFishes++;
    };
    void print() const { printAnimalTable(animals::fish); };
private:
    int numFishes;
};


/* 
other similar classes to fish, but with other animals name
*/

void menu()
{
    cout << "MENU - Please enter a number to select an option" << endl;
    int i = 0;
    for (i; i < static_cast<int>(animals::last); i++)
    {
        cout << i + 1 << " - Insert an " << animals(i) << endl;
    }
}
animal* selectMenu()
{
    animal* ptr = nullptr;
    int option = 0;
    cout << "Enter an option: ";
    cin >> option;
    cin.clear();
    switch (--option)
    {
    case static_cast<int>(animals::fish) : ptr = new fish(); break;
    case static_cast<int>(animals::insects) : ptr = new insects(); break;
    case static_cast<int>(animals::reptiles) : ptr = new reptiles(); break;
    case static_cast<int>(animals::mammals) : ptr = new mammals(); break;
    case static_cast<int>(animals::amphibians) : ptr = new amphibians(); break;
    case static_cast<int>(animals::birds) : ptr = new birds(); break;
    default: ptr = nullptr;
    }
    return ptr;
}
int main() {
    menu();
    unique_ptr<animal> a{ selectMenu() };
    assert(a != nullptr);
    a->push_animal("animal");
    a->printAllAnimals();
    /*a->printAllAnimals();
    a->push_animal("fish");
    cout << a->returnAnimalCount();
    a->printAllAnimals();
    a->print();*/
    system("pause");
    return 0;
}

 

[Stellow]

Admin, I think this post supposed to be on resources, programming, if you move it I would appreciate