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author | Julien Dessaux | 2024-12-16 22:26:23 +0100 |
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committer | Julien Dessaux | 2024-12-16 22:26:23 +0100 |
commit | 9ed8dc9af26b19716616246250553df3ffdf5d37 (patch) | |
tree | 4abf1dc0df1948af80f3afc9cd3e724501a7a487 /2024/13-Claw_Contraption/first.hs | |
parent | 2024-12 in haskell (diff) | |
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2024-13 in haskell
Diffstat (limited to '2024/13-Claw_Contraption/first.hs')
-rw-r--r-- | 2024/13-Claw_Contraption/first.hs | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/2024/13-Claw_Contraption/first.hs b/2024/13-Claw_Contraption/first.hs new file mode 100644 index 0000000..8ed15f9 --- /dev/null +++ b/2024/13-Claw_Contraption/first.hs @@ -0,0 +1,63 @@ +-- requires cabal install --lib megaparsec parser-combinators heap vector +module Main (main) where + +import Control.Monad (void, when) +import Data.Either +import qualified Data.Matrix as MTX +import Data.Ratio +import Data.Void (Void) +import Text.Megaparsec +import Text.Megaparsec.Char + +exampleExpectedOutput = 480 + +type Pair = (Rational, Rational) -- X Y +type Entry = (Pair, Pair, Pair) -- ButtonA ButtonB Prize +type Input = [Entry] + +type Parser = Parsec Void String + +parseNumber :: Parser Rational +parseNumber = fromInteger . read <$> some digitChar + +parseButton :: Parser Pair +parseButton = (,) <$> (string "Button " *> letterChar *> string ": X+" *> parseNumber) + <*> (string ", Y+" *> parseNumber <* eol) + +parsePrize :: Parser Pair +parsePrize = (,) <$> (string "Prize: X=" *> parseNumber) + <*> (string ", Y=" *> parseNumber <* eol) + +parseEntry :: Parser Entry +parseEntry = (,,) <$> parseButton + <*> parseButton + <*> parsePrize + +parseInput' :: Parser Input +parseInput' = some (parseEntry <* optional eol) <* eof + +parseInput :: String -> IO Input +parseInput filename = do + input <- readFile filename + case runParser parseInput' filename input of + Left bundle -> error $ errorBundlePretty bundle + Right input' -> return input' + +-- ax + bx = c +-- ay + by = d +compute :: Input -> Rational +compute = sum . map compute' + where + compute' ((ax, ay), (bx, by), (px, py)) = let (Right sol) = MTX.rref $ MTX.fromList 2 3 [ ax, bx, px + , ay, by, py ] + x = sol MTX.! (1, 3) + y = sol MTX.! (2, 3) + in if (denominator x == 1 && denominator y == 1) then 3 * x + y else 0 + +main :: IO () +main = do + example <- parseInput "example" + let exampleOutput = compute example + when (exampleOutput /= exampleExpectedOutput) (error $ "example failed: got " ++ show exampleOutput ++ " instead of " ++ show exampleExpectedOutput) + input <- parseInput "input" + print $ compute input |