This problem can be solved simply by adding the keyword virtual in front of the function definition in the base class so that during the polymorphism process, the instance can be identified as the subclass instance instead of the base.

Original Code

#include <iostream>
#include <vector>

using namespace std;

class HotelRoom {
public:
    HotelRoom(int bedrooms, int bathrooms) 
    : bedrooms_(bedrooms), bathrooms_(bathrooms) {}
    
    int get_price() {
        return 50*bedrooms_ + 100*bathrooms_;
    }
private:
    int bedrooms_;
    int bathrooms_;
};

class HotelApartment : public HotelRoom {
public:
    HotelApartment(int bedrooms, int bathrooms) 
    : HotelRoom(bedrooms, bathrooms) {}

    int get_price() {
        return HotelRoom::get_price() + 100;
    }
};

int main() {
    int n;
    cin >> n;
    vector<HotelRoom*> rooms;
    for (int i = 0; i < n; ++i) {
        string room_type;
        int bedrooms;
        int bathrooms;
        cin >> room_type >> bedrooms >> bathrooms;
        if (room_type == "standard") {
            rooms.push_back(new HotelRoom(bedrooms, bathrooms));
        } else {
            rooms.push_back(new HotelApartment(bedrooms, bathrooms));
        }
    }

    int total_profit = 0;
    for (auto room : rooms) {
        total_profit += room->get_price();
    }
    cout << total_profit << endl;

    for (auto room : rooms) {
        delete room;
    }
    rooms.clear();

    return 0;
}

Submission

By using the commented cout statements, I realized that only the HotelRoom::get_price is called since all the rooms are identified as HotelRoom instances without the virtual keyword and overloading.

#include <iostream>
#include <vector>

using namespace std;

class HotelRoom {
public:
    HotelRoom(int bedrooms, int bathrooms) 
    : bedrooms_(bedrooms), bathrooms_(bathrooms) {}
    
    virtual int get_price() {
        // cout << "Room:" <<  50*bedrooms_ + 100*bathrooms_ << endl;
        return 50*bedrooms_ + 100*bathrooms_;
    }
private:
    int bedrooms_;
    int bathrooms_;
};

class HotelApartment : public HotelRoom {
public:
    HotelApartment(int bedrooms, int bathrooms) 
    : HotelRoom(bedrooms, bathrooms) {}

    int get_price() {
        // cout << "Apartment: " << HotelRoom::get_price() + 100 << endl;
        return HotelRoom::get_price() + 100;
    }
};

int main() {
    int n;
    cin >> n;
    vector<HotelRoom*> rooms;
    for (int i = 0; i < n; ++i) {
        string room_type;
        int bedrooms;
        int bathrooms;
        cin >> room_type >> bedrooms >> bathrooms;
        if (room_type == "standard") {
            rooms.push_back(new HotelRoom(bedrooms, bathrooms));
        } else {
            rooms.push_back(new HotelApartment(bedrooms, bathrooms));
        }
    }

    int total_profit = 0;
    for (auto room : rooms) {
        total_profit += room->get_price();
    }
    cout << total_profit << endl;

    for (auto room : rooms) {
        delete room;
    }
    rooms.clear();

    return 0;
}