Object-oriented is a difficult concept that is repeatedly explained and organized in an easy-to-understand manner, so it was really fun to listen to. However, since there are not many parts where you listen to the lecture and solve problems yourself, I am worried that I am not able to understand it well... Will I be able to understand it well if I follow the roadmap and practice repeatedly? If not, are there any books or problems that can be used in conjunction with the lecture?