Such problems are very well solved step by step.
Decision one.
Therefore on each step we can improve the last decision without brute force.

haha are you serious about that en passant thing ?

Happy coding ^_^

You have interesting katas, very detailed test cases. Some of the solutions are really mind-blowing, they must be aliens :-)

Yes, now I see in Your solution there is logic behind it. Very surprising to me. I'm wondering if this is possible to invent this logic without rewritting all possible DFA and trying to find relations between them. Is this known mathematical problem with known formula? I didn't find such logic anywhere but I read about DFA and as I remember I had DFA during my mathematical study very long time ago but I have never came accross such logic. Interesting.

Well done. Happy coding ^_^

Nice kata. You put so much work in the detailed surprising test cases, good TDD. I wasn't sure if this problem can be solved without good AI implementation. My solution is far away from perfect and not cover all possible scenarios (like E groups joining or E first choice race) but it was fun, like never ending story, You are smart :-)

Fixed

Not really, brute force is scanning all possible solutions, usuallly always solves but usually has time problem, especially for 7x7 where You have 5040^7 complexity not just 720^6 like it was in case 6x6. Step-by-step is fast but it is partial solution, just guessing numbers like something described here http://www.conceptispuzzles.com/index.aspx?uri=puzzle/skyscrapers/techniques or exactly like You said "trow random numbers into the air" and You can solve specific examples. As I see most of all solutions here are step-by-step, some of them are even descibed like that in comments, that they are not brute force. Probably 8x8 will not be possible with brute force, which in fact means that it will not be possible at all in time (if You are looking for 100% solve solution).

Sorry, only see this now.

Leave it as is, for the foreseeable future.

ATM we only have two solutions anyway (one of which is yours). When people start complaining it's too easy, it'll be early enough to upgrade it.

I don't know what you mean by brute force .. typing all that code? :P

I say well done.

Anybody who solves this in time is my hero, I don't care exactly how you do it - you can't just throw random numbers into the air and have them fall into a solution, you will have to do something smart, even if you consider it brute force.

Happily, The brute force still works fine in time here as well. I guess the step-by-step solution not exists for this kind of problem. You can only solve specific examples with step-by-step. However, I see You did not expect brute force here? Good job anyway.