119 lines
5.9 KiB
Haskell
119 lines
5.9 KiB
Haskell
-- requires cabal install --lib megaparsec parser-combinators heap vector
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module Main (main) where
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import Control.Applicative.Permutations
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import Control.Monad (void, when)
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import qualified Data.Char as C
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import Data.Either
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import Data.Functor
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import qualified Data.Heap as H
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import qualified Data.List as L
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import qualified Data.Map as M
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import Data.Maybe
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import qualified Data.Set as S
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import qualified Data.Vector as V
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import qualified Data.Vector.Unboxed as VU
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import Data.Void (Void)
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import Text.Megaparsec
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import Text.Megaparsec.Char
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import Debug.Trace
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data Pulse = Low | High deriving (Eq, Show)
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data Module = Normal | FlipFlop Bool | Conjunction (M.Map String Pulse) | Broadcaster deriving (Eq, Show)
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data Configuration = Configuration Module String [String] deriving (Eq, Show)
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type Conf = (Module, [String])
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type Input = M.Map String Conf
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type Parser = Parsec Void String
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parseModule :: Parser Module
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parseModule = char '%' $> FlipFlop False
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<|> char '&' $> Conjunction M.empty
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<|> lookAhead (string "broadcaster") $> Broadcaster
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<|> lookAhead letterChar $> Normal
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parseLabel :: Parser String
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parseLabel = some letterChar
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parseConfiguration :: Parser Configuration
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parseConfiguration = Configuration <$> parseModule
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<*> parseLabel <* string " -> "
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<*> some (parseLabel <* optional (string ", "))
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parseInput' :: Parser Input
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parseInput' = M.fromList . map (\(Configuration m s l) -> (s, (m, l))) <$> some (parseConfiguration <* eol) <* eof
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parseInput :: String -> IO Input
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parseInput filename = do
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input <- readFile filename
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case runParser parseInput' filename input of
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Left bundle -> error $ errorBundlePretty bundle
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Right input' -> return input'
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compute :: Input -> Int
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compute input = L.foldl' lcm 1 $ computeX 0 (take (length targets) $ repeat Nothing) $ initConjuctions input
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where
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computeX :: Int -> [Maybe Int] -> Input -> [Int]
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computeX i acc input | all isJust acc = fromJust <$> acc
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| otherwise = let (acc', input') = compute' [("button", Low, "broadcaster")] i acc input
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in computeX (i+1) acc' input'
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compute' :: [(String, Pulse, String)] -> Int -> [Maybe Int] -> Input -> ([Maybe Int], Input)
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compute' signals i acc input | length stepAll == 0 = (acc, input)
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| otherwise = let acc' = map (accStep i stepAll) $ L.zip targets acc
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in compute' stepAll i acc' alterAll
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where
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alterAll :: Input
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alterAll = L.foldl' alterOne input signals
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alterOne :: Input -> (String, Pulse, String) -> Input
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alterOne acc (prev, p, me) = alter p prev me acc (M.lookup me input)
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alter :: Pulse -> String -> String -> Input -> Maybe Conf -> Input
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alter _ _ _ input (Just (Normal, _)) = input
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alter High _ _ input (Just (FlipFlop _, _)) = input
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alter Low _ me input (Just (FlipFlop False, l)) = M.insert me (FlipFlop True, l) input
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alter Low _ me input (Just (FlipFlop True, l)) = M.insert me (FlipFlop False, l) input
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alter p prev me input (Just (Conjunction m, l)) = M.insert me (Conjunction $ M.insert prev p m, l) input
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alter p _ _ input (Just (Broadcaster, l)) = input
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alter _ _ _ input Nothing = input
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stepAll :: [(String, Pulse, String)]
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stepAll = L.foldl' stepOne [] signals
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stepOne :: [(String, Pulse, String)] -> (String, Pulse, String) -> [(String, Pulse, String)]
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stepOne acc (prev, p, s) = step p prev s acc (M.lookup s input)
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step :: Pulse -> String -> String -> [(String, Pulse, String)] -> Maybe Conf -> [(String, Pulse, String)]
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step _ _ _ acc (Just (Normal, _)) = acc
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step High _ _ acc (Just (FlipFlop _, _)) = acc
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step Low _ me acc (Just (FlipFlop False, l)) = acc ++ map (set me High) l
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step Low _ me acc (Just (FlipFlop True, l)) = acc ++ map (set me Low) l
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step p prev me acc (Just (Conjunction m, l)) = let p2 = if length (M.filter (\x -> x == High) $ M.insert prev p m) == length m then Low else High
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in acc ++ map (set me p2) l
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step p _ me acc (Just (Broadcaster, l)) = acc ++ map (set me p) l
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step _ _ _ acc Nothing = acc
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initConjuctions :: Input -> Input
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initConjuctions input = let r = M.foldrWithKey initConf input input in r
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initConf :: String -> Conf -> Input -> Input
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initConf c (_, l) input = L.foldl' initOne input l
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where
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initOne :: Input -> String -> Input
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initOne input s = case M.lookup s input of
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Just (Conjunction m, l) -> M.insert s (Conjunction (M.insert c Low m), l) input
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_ -> input
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set :: String -> Pulse -> String -> (String, Pulse, String)
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set me p s = (me, p, s)
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targets = pointsTo toRx
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[toRx] = pointsTo "rx"
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pointsTo :: String -> [String]
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pointsTo name = L.foldl' (\acc (k, (_, l)) -> if isJust (L.elemIndex name l) then k:acc else acc) [] $ M.assocs input
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accStep :: Int -> [(String, Pulse, String)] -> (String, Maybe Int) -> Maybe Int
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accStep _ _ (_, Just x) = Just x
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accStep i stepAll (t, Nothing) | triggered = Just (i + 1)
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| otherwise = Nothing
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where
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triggered = L.foldl' (trigg t) False stepAll
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trigg _ True _ = True
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trigg t False (_, Low, u) = t == u
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trigg _ _ _ = False
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main :: IO ()
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main = do
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input <- parseInput "input"
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print $ compute input
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