I've made some simple test cases for the problem CAR :)
Here is the link.
https://pan.baidu.com/s/1c4Qmlg

How are you supposed to download? Not everybody nows chinese/japanese/whatever.

Right click -> Translate to English (or non-Chrome equivalent)

Or just click on the download icon, it's a standard one.

I have the same outs.

Me too :)

The tests are invalid. "Every new tile (except the first one) must be adjacent to another tile already on board."

Out of curiosity, can I ask you what are your times for these tests?

On these tests, my machine, I get 1.25s (on the second test, first one is faster). The judge is a lot slower though... I tried testing on random tests on testrun, the worst I got was 4s when I randomly marked 1/7 of the board, which isn't great.

Sorry for the invalid data..
I generate a new one..
I hope this one is valid
https://pan.baidu.com/s/1hsw67aO

I confirm these new outs are correct (dunno about ins, don't care ;p)

I confirm the last archive too

I confirm these new outs.