Day 3: Lobby

Megathread guidelines

  • Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
  • You can send code in code blocks by using three backticks, the code, and then three backticks or use something such as https://topaz.github.io/paste/ if you prefer sending it through a URL

FAQ

  • LeixB@lemmy.world
    1·
    2 months ago

    Haskell

    I think I could have avoided the minimumBy hack by doing another reverse and changing the indices.

    import Data.List
import Data.Function
import Control.Arrow

parse = fmap (fmap (read . pure)) . lines

solve n = sum . fmap (sum . zipWith (*) (iterate (*10) 1) . reverse . go n)
  where
    go :: Int -> [Int] -> [Int]
    go 0 l = pure $ maximum l
    go n l = mx : go (n-1) (drop idx l)
      where
        -- use minimumBy since if there are multiple least elements, we want the leftmost one.
        (idx, mx) = minimumBy (compare `on` (negate . snd)) . zip [1..] . take (length l - n) $ l

main = getContents >>= print . (solve 1 &&& solve 11) . parse