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import Data.List
type Stone = Int
atoi :: String -> Stone
atoi = read
maybeSplitDigs :: Stone -> Maybe (Stone, Stone)
maybeSplitDigs s
| even ln = Just (s `divMod` md)
| otherwise = Nothing
where
ln = ceiling $ logBase 10 $ fromIntegral s
md = 10 ^ (ln `div` 2)
blink :: [Stone] -> [Stone] -> [Stone]
blink acc [] = reverse acc
blink acc (h:t)
| h == 0 =
blink (1:acc) t
| h == 1 =
blink (2024:acc) t
| Just (left, right) <- maybeSplitDigs h =
blink (right:left:acc) t
| otherwise =
blink (h * 2024:acc) t
consume :: String -> [Stone]
consume = map atoi . words
applyN :: Int -> (a -> a) -> a -> a
applyN n f = foldr (.) id (replicate n f)
part1 :: [Stone] -> Int
part1 = length . applyN 25 (blink [])
part2 :: [Stone] -> Int
part2 = length . applyN 75 (blink [])
main = do
file <- readFile "day11.input"
let stones = consume file
putStrLn ("Part 1: " ++ (show $ part1 stones))
--putStrLn ("Part 2: " ++ (show $ part2 stones))
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