71 lines
2.5 KiB
Haskell
71 lines
2.5 KiB
Haskell
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import Data.Sequence (Seq, fromList, index)
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import Data.Vector.Unboxed (Vector, (!), (//))
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import qualified Data.Vector.Unboxed as V (replicate)
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type Registers = Vector Int
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type State = (Registers, Int, Int, Int)
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type Instruction = State -> State
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data Value = Register Char | Number Int
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getIndex :: Value -> Int
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getIndex (Register c) = case c of
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'a' -> 0
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'b' -> 1
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'f' -> 2
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'i' -> 3
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'p' -> 4
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getValue :: Value -> Registers -> Int
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getValue value registers = case value of
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Number i -> i
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c -> registers ! (getIndex c)
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parseValue :: String -> Value
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parseValue str =
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Register $ head str -- TODO: implement correctly!
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son :: Value -> State -> State
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son freq (reg, pos, _, rec) =
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(reg, pos + 1, getValue freq reg, rec)
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rcv :: Value -> State -> State
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rcv v (reg, pos, freq, rec) =
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(reg, pos + 1, freq, if getValue v reg == 0 then rec else freq)
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app :: (Int -> Int -> Int) -> Value -> Value -> State -> State
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app f i v (reg, pos, freq, rec) =
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let index = getIndex i
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value = getValue v reg
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in (reg // [(index, reg ! index `f` value)], pos + 1, freq, rec)
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jgz :: Value -> Value -> State -> State
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jgz condition offset (reg, pos, freq, rec) =
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(reg, pos + if getValue condition reg > 0 then getValue offset reg else 1, freq, rec)
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parseLine :: String -> State -> State
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parseLine str =
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let op : vs = words str
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in case op of
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"snd" -> son $ parseValue $ head vs
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"set" -> app const (parseValue $ head vs) (parseValue $ last vs)
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"add" -> app (+) (parseValue $ head vs) (parseValue $ last vs)
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"mul" -> app (*) (parseValue $ head vs) (parseValue $ last vs)
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"mod" -> app mod (parseValue $ head vs) (parseValue $ last vs)
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"rcv" -> rcv $ parseValue $ head vs
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"jgz" -> jgz (parseValue $ head vs) (parseValue $ last vs)
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-- precondition: pos < length instructions
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executeNextInstruction :: Seq Instruction -> State -> State
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executeNextInstruction instructions (reg, pos, freq, rec) =
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instructions `index` pos $ (reg, pos, freq, rec)
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recover :: Seq Instruction -> State -> Int
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recover instructions (reg, pos, freq, rec) =
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if rec /= 0 then rec else
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recover instructions $ executeNextInstruction instructions (reg, pos, freq, rec)
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main :: IO ()
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main = do
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instructions <- fmap (fromList . map parseLine . lines) $ readFile "18.hs"
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let initialState = (V.replicate 5 0, 0, 0, 0)
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print $ recover instructions initialState
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