Day 10: Hoof It
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
- What is this?: Here is a post with a large amount of details: https://programming.dev/post/6637268
- Where do I participate?: https://adventofcode.com/
- Is there a leaderboard for the community?: We have a programming.dev leaderboard with the info on how to join in this post: https://programming.dev/post/6631465
Haskell
Cool task, nothing to optimize
import Control.Arrow import Data.Array.Unboxed (UArray) import Data.Set (Set) import qualified Data.Char as Char import qualified Data.List as List import qualified Data.Set as Set import qualified Data.Array.Unboxed as UArray parse :: String -> UArray (Int, Int) Int parse s = UArray.listArray ((1, 1), (n, m)) . map Char.digitToInt . filter (/= '\n') $ s where n = takeWhile (/= '\n') >>> length $ s m = filter (== '\n') >>> length >>> pred $ s reachableNeighbors :: (Int, Int) -> UArray (Int, Int) Int -> [(Int, Int)] reachableNeighbors p@(py, px) a = List.filter (UArray.inRange (UArray.bounds a)) >>> List.filter ((a UArray.!) >>> pred >>> (== (a UArray.! p))) $ [(py-1, px), (py+1, px), (py, px-1), (py, px+1)] distinctTrails :: (Int, Int) -> UArray (Int, Int) Int -> Int distinctTrails p a | a UArray.! p == 9 = 1 | otherwise = flip reachableNeighbors a >>> List.map (flip distinctTrails a) >>> sum $ p reachableNines :: (Int, Int) -> UArray (Int, Int) Int -> Set (Int, Int) reachableNines p a | a UArray.! p == 9 = Set.singleton p | otherwise = flip reachableNeighbors a >>> List.map (flip reachableNines a) >>> Set.unions $ p findZeros = UArray.assocs >>> filter (snd >>> (== 0)) >>> map fst part1 a = findZeros >>> map (flip reachableNines a) >>> map Set.size >>> sum $ a part2 a = findZeros >>> map (flip distinctTrails a) >>> sum $ a main = getContents >>= print . (part1 &&& part2) . parse