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.

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 :-)

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).

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.

You are very funny boy, I guess You need to try something harder :-)

Thanks for new 1 kyu kata.

Thanks for next 1 kyu kata. Nice kata, well-described and well-prepared, I like the non-image chess board in the description and log. I have been playing chess since I was born but first time I have read about en passant. People learn all their life and finally they die stupid :-)

Thanks for next 1 kyu kata.