diff options
Diffstat (limited to '2020')
-rw-r--r-- | 2020/17-Conway_Cubes/example | 3 | ||||
-rw-r--r-- | 2020/17-Conway_Cubes/first.hs | 55 | ||||
-rw-r--r-- | 2020/17-Conway_Cubes/input | 8 |
3 files changed, 66 insertions, 0 deletions
diff --git a/2020/17-Conway_Cubes/example b/2020/17-Conway_Cubes/example new file mode 100644 index 0000000..eedd3d2 --- /dev/null +++ b/2020/17-Conway_Cubes/example @@ -0,0 +1,3 @@ +.#. +..# +### diff --git a/2020/17-Conway_Cubes/first.hs b/2020/17-Conway_Cubes/first.hs new file mode 100644 index 0000000..891689c --- /dev/null +++ b/2020/17-Conway_Cubes/first.hs @@ -0,0 +1,55 @@ +module Main (main) where +import Control.Monad (when) +import Data.List (foldl') +import Data.Map qualified as M +import System.Exit (die) + +exampleExpectedOutput = 112 + +type Coord = (Int, Int, Int) +type Input = M.Map Coord Bool + +parseInput :: String -> IO Input +parseInput filename = do + input <- readFile filename + return . M.fromList . fst $ foldl' process ([], (0, 0, 0)) input + where + process :: ([(Coord, Bool)], Coord) -> Char -> ([(Coord, Bool)], Coord) + process (acc, (x, y, z)) c = case c of + '.' -> (acc, (x+1, y, z)) + '#' -> (((x, y, z), True):acc, (x+1, y, z)) + '\n' -> (acc, (0, y+1, z)) + +complete :: Input -> Input +complete input = M.foldrWithKey process M.empty input + where + process :: Coord -> Bool -> Input -> Input + process (x, y, z) False acc = acc + process (x, y, z) True acc = M.unions [M.singleton (x, y, z) True, acc, M.fromList [((x+a, y+b, z+c), False) | a<-[-1..1], b<-[-1..1], c<-[-1..1]]] + +step :: Int -> Input -> Input +step 0 input = input +step n input = step (n-1) (M.foldrWithKey evolve M.empty input') + where + input' = complete input + evolve :: Coord -> Bool -> Input -> Input + evolve (x, y, z) s acc = case s of + False -> M.insert (x, y, z) (actives == 3) acc + True -> M.insert (x, y, z) (actives == 3 || actives == 4) acc + where + actives = length . filter id $ [lookup (x+a, y+b, z+c) | a<-[-1..1], b<-[-1..1], c<-[-1..1]] + lookup :: Coord -> Bool + lookup c = case M.lookup c input' of + Just True -> True + otherwise -> False + +compute :: Input -> Int +compute input = M.size . M.filter id $ step 6 input + +main :: IO () +main = do + example <- parseInput "example" + let exampleOutput = compute example + when (exampleOutput /= exampleExpectedOutput) (die $ "example failed: got " ++ show exampleOutput ++ " instead of " ++ show exampleExpectedOutput) + input <- parseInput "input" + print $ compute input diff --git a/2020/17-Conway_Cubes/input b/2020/17-Conway_Cubes/input new file mode 100644 index 0000000..0a30565 --- /dev/null +++ b/2020/17-Conway_Cubes/input @@ -0,0 +1,8 @@ +.#.#..## +..#....# +##.####. +...####. +#.##..## +#...##.. +...##.## +#...#.#. |