Design a Music Player like Spotify with below methods int addSong(string songTitle); // add a song to your music player with incremental song ids starting from 1 void playSong(int songId, int userId); // user plays a song that is present in the music player void printMostPlayedSongs(); // print song titles in decreasing order of number of unique users' plays Follow up vector getLastThreeSongs(int userId); // get last 3 unique songs played by a given user There was another follow up as well which the recruiter mentioned post the interview. Couldn't get time for that.