I was talking about the Little Puss mode. Thanks for the hints, but I got my own strategy (kinda). Right now, I think I have to change it a bit, because Headteacher always lets Marzia out of the first corridor since the last updates.
I entered all 9 codes. I guess I'm just too slow for this game... Yeah, I noticed that sometimes the notebooks are in the locked rooms. Really? Marzia opens doors by herself now? Great, now I have to change my entire strategy...