Board-Independent Status Indicator

#include <iostream>
using namespace std;

/*
Select exactly ONE hardware board at build time.
*/
 //#define BOARD_TYPE_A
#define BOARD_TYPE_B

// Abstract interface used by application code
class StatusIndicator {
public:
    virtual void toggle() = 0;
    virtual bool isOn() const = 0;
    virtual ~StatusIndicator() = default;
};

/*
TASK FOR LEARNER:

- Create TWO board-specific implementations of StatusIndicator

- Select exactly one using conditional compilation
- Enforce compile-time errors for invalid selections
- Implement the factory function below

DO NOT modify main()
*/
class BoardA_Indicator:public StatusIndicator{
    bool state = false ;
    public:
    void toggle() override {state = !state;}
    bool isOn() const override {return state;}

};
class BoardB_Indicator : public StatusIndicator {
    bool state = false;
public:
    void toggle() override { state = !state; }
    bool isOn() const override { return state; }
};
// Factory function declaration (not implemented here)
StatusIndicator& getStatusIndicator();

StatusIndicator& getStatusIndicator() {
    #if defined(BOARD_TYPE_A)
        static BoardA_Indicator indicator;
        return indicator;
    #elif defined(BOARD_TYPE_B)
        static BoardB_Indicator indicator;
        return indicator;
    #else
        #error "Chua chon Board Type!"
    #endif
    }

int main() {
    int n;
    cin >> n;

    StatusIndicator& indicator = getStatusIndicator();

    for (int i = 0; i < n; ++i) {
        int evt;
        cin >> evt;

        if (evt == 1) {
            indicator.toggle();
        }

        cout << (indicator.isOn() ? "STATUS=ON\n" : "STATUS=OFF\n");
    }

    return 0;
}