56 lines
1.5 KiB
Haskell
56 lines
1.5 KiB
Haskell
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import Data.HashMap (Map, insert, alter, empty, toList)
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import qualified Data.HashMap as M (lookup)
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import Debug.Trace
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data Instruction = I {
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reg :: String,
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inc :: Int,
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src :: String,
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fnc :: Int -> Bool
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}
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getFnc :: String -> (Int -> Int -> Bool)
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getFnc s = case s of
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"<" -> (<)
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"<=" -> (<=)
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">" -> (>)
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">=" -> (>=)
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"==" -> (==)
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"!=" -> (/=)
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getOrSetZero :: String -> Map String Int -> (Int, Map String Int)
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getOrSetZero s m =
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case M.lookup s m of
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Just value -> (value, m)
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Nothing -> (0, insert s 0 m)
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addToMaybe :: Int -> Maybe Int -> Maybe Int
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addToMaybe i (Just x) = Just $ i + x
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addToMaybe i Nothing = Just i
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parseLine :: String -> Instruction
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parseLine s =
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let (register : command : value : _ : source : function : argument : _) = words s
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in I {
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reg = register,
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inc = case command of
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"inc" -> read value
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"dec" -> (- read value),
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src = source,
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fnc = flip (getFnc function) $ read argument
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}
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executeInstruction :: Map String Int -> Instruction -> Map String Int
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executeInstruction m (I r i s f) =
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let (value, newMap) = getOrSetZero s m
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in if f value
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then alter (addToMaybe i) r newMap
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else newMap
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main :: IO ()
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main = do
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input <- readFile "8.txt"
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let instructions = map parseLine $ lines input
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finalMap = foldl executeInstruction empty instructions
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maxValue = maximum . snd . unzip . toList $ finalMap
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print $ maxValue
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