HackerRank, c++, Messages Order

간단한 static, class , operator문제.

class Message {
private:
    string _msg;
    static int _id;
    int myId;
public: 
    Message() {}
    Message(string msg) : _msg(msg) {
        myId = _id++;
    } 
    const string& get_text() {
        return _msg;
    }
    
    int getMyId() {
        return myId;
    }
    bool operator<(Message a)
    {
        return myId < a.myId;
    }
};
int Message::_id = 0;
class MessageFactory {
public:
    MessageFactory() {}
    Message create_message(const string& text) {
        Message *msg = new Message(text);
        return *msg;
    }
};