48 lines
1.7 KiB
Haskell
48 lines
1.7 KiB
Haskell
import Aoc
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import Data.Char ( isDigit )
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import Data.Bits
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data Op = AND | OR | SHIFTL | SHIFTR | NOT | CONST
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deriving (Show, Eq)
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parseFile :: [String] -> [(String, (Op, String, String))] -- [(out, (op, arg1, arg2))]
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parseFile = map (\line ->
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let (expr, ["->", out]) = lastSplit 2 $ words line in
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(out, case expr of
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[arg1, "AND", arg2] -> (AND, arg1, arg2)
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[arg1, "OR", arg2] -> (OR, arg1, arg2)
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[arg1, "LSHIFT", arg2] -> (SHIFTL, arg1, arg2)
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[arg1, "RSHIFT", arg2] -> (SHIFTR, arg1, arg2)
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["NOT", arg] -> (NOT, arg, "")
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[arg] -> (CONST, arg, "")))
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eval :: Op -> Int -> Int -> Int
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eval OR = (.|.)
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eval AND = (.&.)
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eval SHIFTR = shiftR
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eval SHIFTL = shiftL
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eval CONST = const
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eval NOT = \a _-> complement a
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eval' :: Op -> Int -> Int -> Int
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eval' op arg1 arg2 = (.&. 0xFFFF) $ eval op arg1 arg2
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eval'' :: [(String, (Op, String, String))] -> [(String, Int)] -> String -> (Int, [(String, Int)])
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eval'' wires memos label = case lookup label memos of
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Just value -> (value, memos)
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Nothing -> case lookup label wires of
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Just (op, arg1, arg2) ->
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let (val1, memos1) = eval'' wires memos arg1 in
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let (val2, memos2) = eval'' wires memos1 arg2 in
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let val = eval' op val1 val2 in
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(val, (label, val):memos2)
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Nothing -> (if all isDigit label then read label else undefined, memos) -- if null label then 0 else
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part1 :: [(String, (Op, String, String))] -> Int
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part1 wires = fst $ eval'' wires [] "a"
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part2 :: [(String, (Op, String, String))] -> Int -> Int
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part2 wires part1Answer = fst $ eval'' wires [("b", part1Answer)] "a"
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main :: IO ()
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main = aocMain' parseFile (passthrough . part1) part2 |