According to an interview I watched the director anticipated the door code to earlier in the show. They were going to have two different challenges like how they have different puzzles each day in prison. Also the AI for 5 in a row was set at the easiest setting
I wonder what the producers would have done if no one cracked the code. The fact that this happened the very last time someone went to jail makes me wonder if production left some clues specially for See-won to find...