diff options
| -rw-r--r-- | 2021/11.hs | 36 | ||||
| -rw-r--r-- | 2021/11.in | 10 |
2 files changed, 38 insertions, 8 deletions
@@ -1,15 +1,16 @@ -{-# OPTIONS -Wno-type-defaults #-} +{-# LANGUAGE MultiWayIf #-} module Main where import qualified Data.Array as A -import Data.List -import Data.Maybe +import Data.List (findIndex) +import Data.Maybe (fromJust) +import Data.Monoid (Sum(..)) import Input -stencil8 :: (a -> [a] -> b) -> a -> A.Array (Int, Int) a -> A.Array (Int, Int) b -stencil8 f def arr = +stencil8 :: a -> (a -> [a] -> b) -> A.Array (Int, Int) a -> A.Array (Int, Int) b +stencil8 def f arr = A.listArray (A.bounds arr) [f (arr A.! (y, x)) [get (yi, xi) @@ -22,10 +23,29 @@ stencil8 f def arr = | otherwise = def ((y1, x1), (y2, x2)) = A.bounds arr -step1 :: A.Array (Int, Int) Int -> A.Array (Int, Int) Int -step1 = stencil _ 0 +amap :: A.Ix i => (a -> b) -> A.Array i a -> A.Array i b +amap f a = A.listArray (A.bounds a) (map f (A.elems a)) + +flash :: A.Array (Int, Int) Int -> A.Array (Int, Int) Int +flash = stencil8 0 $ \v env -> if | v < 0 -> v + | v > 9 -> -1 + | otherwise -> v + sum (map (fromEnum . (>9)) env) + +step :: A.Array (Int, Int) Int -> (Sum Int, A.Array (Int, Int) Int) +step a = + let a' = fixpoint flash (amap (+1) a) + in (Sum (length [() | -1 <- A.elems a']), amap (\v -> if v < 0 then 0 else v) a') + where fixpoint f x = let y = f x in if y == x then x else fixpoint f y + +display :: A.Array (Int, Int) Int -> String +display arr = unlines + [concat [show (arr A.! (y, x)) | x <- [x1..x2]] | y <- [y1..y2]] + where ((y1, x1), (y2, x2)) = A.bounds arr main :: IO () main = do inp <- getInput 11 - return () + let arr0 = A.listArray ((1, 1), (length inp, length (head inp))) (concatMap (map (read . pure)) inp) + let states = iterate (>>= step) (return arr0) + print (getSum (fst (states !! 100))) + print (fromJust $ findIndex (all (== 0) . A.elems) (map snd states)) diff --git a/2021/11.in b/2021/11.in new file mode 100644 index 0000000..07abafe --- /dev/null +++ b/2021/11.in @@ -0,0 +1,10 @@ +3322874652 +5636588857 +7755117548 +5854121833 +2856682477 +3124873812 +1541372254 +8634383236 +2424323348 +2265635842 |