advent01/src/advent01.hs

   1 import Data.Text (Text)
   2 import qualified Data.Text.IO as TIO
   3
   4 import Data.Void (Void)
   5
   6 import Text.Megaparsec
   7 import Text.Megaparsec.Char
   8 import qualified Text.Megaparsec.Char.Lexer as L
   9 import qualified Control.Applicative as CA
  10
  11
  12 main :: IO ()
  13 main = do
  14         text <- TIO.readFile "data/advent01.txt"
  15         let changes = successfulParse text
  16         print $ part1 changes
  17         print $ part2 changes
  18
  19
  20 part1 :: [Int] -> Int
  21 part1 = sum . map fuelRequired
  22
  23 part2 :: [Int] -> Int
  24 part2= sum . map fuelForFuel
  25
  26
  27 fuelRequired :: Int -> Int
  28 fuelRequired m = (m `div` 3) - 2
  29
  30 fuelForFuel :: Int -> Int
  31 fuelForFuel = sum . takeWhile (> 0) . drop 1 . iterate fuelRequired
  32
  33
  34 -- Parse the input file
  35 type Parser = Parsec Void Text
  36
  37 sc :: Parser ()
  38 sc = L.space (skipSome spaceChar) CA.empty CA.empty
  39 -- sc = L.space (skipSome (char ' ')) CA.empty CA.empty
  40
  41
  42 lexeme  = L.lexeme sc
  43 integer = lexeme L.decimal
  44 -- signedInteger = L.signed sc integer
  45
  46 moduleP = many integer
  47
  48 successfulParse :: Text -> [Int]
  49 successfulParse input =
  50         case parse moduleP "input" input of
  51                 Left  _err -> [] -- TIO.putStr $ T.pack $ parseErrorPretty err
  52                 Right changes -> changes