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?

how exatcly does the number get added to the cache?

did you find out?

this is way not 5kyu.. i have finished many 5, but lost on this

very clever. but why isn't this best practice too?

a time to run next to solutions

So many have said it before, the top rated solutions are the shortest not the best. IMPLEMENT A TIME TO RUN NEXT TO THE SOLUTION. We need the overall best not the shortest code to learn.

I think I get it but can you explain why r -= names.size then r/2? I get r/2 and [n1,n2] == r and [n1,n1,n2,n2]. and just r-=names.size makes sense too but the order doesnt

if r=52, names.size= 5... 51-5/2 = 46/2 = 23.. 23-5/2=9.. 9-5/2=2.. names[2] = penny correcly

I see. so "a,b(4,10) = 10, 14" and the next loop is "a,b(10,14) = 14, 24". And the range is like "while i < n ..."? and the "sum,_" the _ tells the fx we don't need that value? Thanks!