Where is 8x8 and 9x9 skyscrapers?

You forgot to turn off wallhack. Git gud.

This warning originates from the test suite, where random sampling from a set is performed. In the latest python version, this is a deprecated feature. A fix is in order. EDIT: a fix ha already been published.

This one here was pretty tough, I really enjoyed it.

yes

What about 2-digit sequences? Do they count?

your code passes that test ("single solution"). Either that's not the problem you're facing, or you should reset the trainer.

Closing

According to your tests, this grid is invalid:

[1, 0, 0, 0, 0, 0, 4, 7, 0]
[0, 8, 0, 2, 0, 4, 0, 1, 0]
[0, 6, 5, 0, 0, 0, 0, 0, 9]
[0, 0, 0, 0, 0, 1, 0, 9, 0]
[0, 0, 0, 3, 5, 0, 0, 0, 0]
[0, 7, 6, 0, 0, 9, 0, 0, 8]
[2, 0, 0, 5, 0, 0, 7, 4, 0]
[0, 0, 0, 0, 1, 8, 0, 0, 0]
[0, 3, 0, 7, 0, 0, 0, 0, 0]

Edit: OK, scratch that, apparently the problem was caused by another grid, not this one. I updated my solution to deal with those scenarios. Is there a way to delete the previous solution if it turned out to be not 100% correct?

Love these puzzles )) My solution for 6x6 almost worked here, just failed on the "Medved's" test, probably because it didn't have trial and error logic implemented yet. Anyway, after a couple of days of tweaking, I managed to pass all of the tests in about 180ms.

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When trying to run a full test suite I keep getting "DeprecationWarning: Sampling from a set deprecated". I'm not even using any sets in my solution, only lists and a dictionary.

Well this is strange. For me, it was not only posible to check for invalid paths of "C" type, but also the site did not seem to intentionally slow down anything for me. Interesting. At some point, the site apparently went malicious.

I find it near impossible to check for invalid paths of the "C" type. One thing i tried to do is to document the coordinates of EVERY point I visit (not just corners), but it takes a while to process. Also, it looks like this website intentionally slows things down. Even the bruteforce solution runs pretty fast on my system, but here it times out after just 1 test.

me weeps in C++ as a first language

Who said anything about C++ ?

I did it in Python which can be OO but also can be functional, dynamic, procedural etc. Nobody should learn C++ as their first language.
The Kata isn't only available in C++ but in lots of other languages.