note: the button ‘forum’ of the medium puzzle ‘green valleys’ does not bring to its specific forum page. i created this one.
i got 100% on tests, but last validator (alps and valleys) failed. i was ready to ask for some help, but i remembered to do some customized tests, and could find a bug in my code just with that quite tiny test (honestly, I found it with a bit of random):
1 3 1
3 1 2
2 3 1
so, in short, when at least one of your validators fails and no none of your tests, create your own customized tests. even small tests should help to debug.
I am quite sure already said in other posts, but this is the second time I face this pattern.