It depends what the class was for. I had a sort of similar experience with a physics class where the professor would take a break mid-exam and just give everyone the answers, but it was a class that was a prerequisite for engineering students who didn't care and really didn't need to, and also a stepping stone for the passionate physics students who did care, but would do the heavy lifting later. The prof was well-regarded for spending his time more on helping with true understanding for the students who cared.