Typing by hand is an underrated option. Inevitably there's gonna be transcription errors, so you'll have to correct them and in the process understand the code.

Typing by hand is an underrated option. Inevitably there's gonna be transcription errors, so you'll have to correct them and in the process understand the code. Also, just take a moment at the end of a chapter to review the code and make sure it follows. I thought that it wasn't doing much either until I realized I actually understood what was going on! After that, you could maybe port it to a different language. But doing that the first time around would be a little hard. Especially if you wanted to keep the code idiomatic to the language.