Day 2: Red-Nosed Reports

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://blocks.programming.dev/ if you prefer sending it through a URL

FAQ

  • LeixB@lemmy.world
    2·
    10 days ago

    Haskell

    Had some fun with arrows.

    import Control.Arrow
import Control.Monad

main = getContents >>= print . (part1 &&& part2) . fmap (fmap read . words) . lines

part1 = length . filter isSafe
part2 = length . filter (any isSafe . removeOne)

isSafe = ap (zipWith (-)) tail >>> (all (between 1 3) &&& all (between (-3) (-1))) >>> uncurry (||)
 where
  between a b = (a <=) &&& (<= b) >>> uncurry (&&)

removeOne [] = []
removeOne (x : xs) = xs : fmap (x :) (removeOne xs)