For some time I have been doing The Times daily Su Doku puzzle. I have to make some effort to keep up with events in Blighty and apparently this is all the rage. My parents first introduced me to it last November – they're devotees too. Since appearing in The Times, it's spread to other newspapers, which enables me to feed my 2-or-3-puzzle-a-day habit.
Having regularly defeated The Times “fiendish” rating for a while now, I'm feeling ready for the challenge of the hardest Su Doku puzzle yet. Being physically removed, I won't actually be able to enter the contest, but I'm looking forward to seeing the puzzles. I have until October to further hone my skills.
That looks like fun – so simple, yet so difficult. Do you solve them out on paper? How intense would a program be that could solve these? I never really got that Big-O stuff.
(http://livejournal.com/users/greatbiggary)
I solve them on paper.
It's simple to solve them programmatically by brute force. And it's not too hard to make a program that applies rules in turn. Just an application of set combinations, really. There are several solvers around on the web. The better ones use rules and tell you for each step how they came to their decision.
(http://livejournal.com/users/elbeno)