AoC/2022/day11/day11.hs
2022-12-11 19:03:28 +01:00

95 lines
2.3 KiB
Haskell

{-# LANGUAGE TemplateHaskell #-}
import Control.Lens
import Data.List
import Data.List.Split
import Data.Maybe
data Monkey =
Monkey
{ mID :: Int
, _items :: [Int]
, operation :: Int -> Int
, test :: Int
, nextMonkey :: (Int, Int)
, _inspectCounter :: Int
}
makeLenses ''Monkey
instance Show Monkey where
show (Monkey a b c d (e, f) g) =
"Monkey " ++
show a ++
":\n Items: " ++
show b ++
"\n Operation: e.g. 1 -> " ++
show (c 1) ++
", 2 -> " ++
show (c 2) ++
"\n Test: divisible by " ++
show d ++
"\n If true: throw to monkey " ++
show e ++
"\n If false: throw to monkey " ++
show f ++ "\nThis monkey has inspected " ++ show g ++ " items.\n"
main :: IO ()
main = do
input <- map (map (splitOn ":") . lines) . splitOn "\n\n" <$> readFile "input"
let monkes = mapMaybe parseMonkey input
print $ day11 20 (`div` 3) monkes
print $ day11 10000 id monkes
day11 :: Int -> (Int -> Int) -> [Monkey] -> Int
day11 x f m = g $ take (succ x) $ iterate (turns f) m
where
g = product . take 2 . reverse . sort . map _inspectCounter . last
parseMonkey :: [[String]] -> Maybe Monkey
parseMonkey [[a, _], [_, b], [_, c], [_, d], [_, e], [_, f]] =
Just $
Monkey
(f' a)
(read ('[' : b ++ "]"))
(parseOP $ words c)
(f' d)
(f' e, f' f)
0
where
f' = read . last . words
parseOP [_, _, _, x, y]
| y == "old" = (^ (2 :: Int))
| x == "*" = (*) (read y)
| otherwise = (+) (read y)
parseMonkey _ = Nothing
turns :: (Int -> Int) -> [Monkey] -> [Monkey]
turns f = turns' 0
where
turns' n ms
| length ms == n = ms
| otherwise = turns' (succ n) monkeNew
where
itemsNew =
[f $ flip mod modNum $ operation (ms !! n) x | x <- _items (ms !! n)]
monkeEmptied =
ms &
ix n .~ ((ms !! n) & items .~ [] & inspectCounter +~ length itemsNew)
monkeNew = monkeThrow itemsNew n monkeEmptied
modNum = foldl1 lcm $ map test ms
monkeThrow :: [Int] -> Int -> [Monkey] -> [Monkey]
monkeThrow (x:xs) n ms =
monkeThrow
xs
n
(ms & ix next .~ ((ms !! next) & items .~ (_items (ms !! next) ++ [x])))
where
next =
if mod x (test (ms !! n)) == 0
then fst targets
else snd targets
targets = nextMonkey (ms !! n)
monkeThrow _ _ ms = ms