1st/1st.cpp

class Device {
public:
    virtual void turnOn() = 0;
    virtual void turnOff() = 0;
    virtual ~Device() {}
};

class LED : public Device {
public:
    void turnOn() override {
        // 點亮 LED
    }
    void turnOff() override {
        // 熄滅 LED
    }
};