| xA yA 1|
| xB yB 1| = 0
| xC yC 1|

Could someone explain this to me more detail or simpler (some reference maybe)? Sorry, but I dont understand at this part.

Sorry, I think i am not thorough enough to understand the example.

May I ask? Are the clues in the description are not always absolute? So, do we have to evaluate each clues? Because in the example, when I see a clue with the value of 4, its just only 2 skyscrappers have been sen.

Maybe you need to test the regex again, because the regex is working fine. And I have to acknowledge it, that this is the cleverest solution I've ever seen. If you test the regex using java find method, the result will be returned very finely (The inner working of Find Method I think). Anyway this is the best solution to reduce the complexity of code.

Nice kata, even though, you still need to visualize your description in the kata before this algebraic isomorphism (isomorphism kata). I had difficulty of understanding the ISO Class, because there is no visualization at all. I think this kata don't need too much logic in it, but It need someone to learn the syntax of their own language. Anyway, this is nice kata, helpful to me for learning the depth syntax of language.

Thanks for your help rosenkranz.

Is it beacuse the picture shows free space, so the array should be 25 and the free space count as " " or ""? The detail shows that just 24 card returned in an array, Am I wrong? Since, I can't debug the test code, because there is no parameter passing, so the test code in server side decides the result and we don't know about the test code in server side.

same for me too, why we got this error, even if the return array is wright, and I have tried it in netbeans too and it's work.

Why I got errors of NullPointerException in the submit of compiler? I have tried my code in netbeans and it's working. Even the tests, it's succeed.