The description looks good.

what does -> do?
where is row declared in valid9?
can someone explain the code please?

couldn't you avoid the "series whose unique numbers add up to 45 but are not valid sudoku wins. For example 2, 2, 9, 9, 6, 1, 8, 14, 5 or 0, 0, 0, 0, 0, 0, 0, 45. " by doing row.uniq.size == 9

what does -> do?
where is row declared in valid9?
can someone explain the code please?

credit to @marksiemers for i/9/3*3 + i%9/3 == x

@herathe - I dislike the monkeypatching of Array =\

Likely code runner server performance issues, check: https://codewars.statuspage.io/

Likely code runner server performance issues, check: https://codewars.statuspage.io/

That one is a fake! :)

Clever, but certainly does not work. One could easily include a number of series whose unique numbers add up to 45 but are not valid sudoku wins. For example 2, 2, 9, 9, 6, 1, 8, 14, 5 or 0, 0, 0, 0, 0, 0, 0, 45. These tests should have been included. This is excellent refactoring, but not excellent code.

Description isn't clear. The given link had a better explanation of expected output. More examples would be useful.

Maybe the problem was changed, but this wasn't a problem for me.

I guess the docs don't explicitly mention that all? short-circuits too. The same is true of none? and any?, by the way.

Temporary objects will be created in memory anyways. I prefer to avoid line wrapping and indent-nesting when possible.

Also updated valid9 criteron because there was no guarantee of only positive numbers.