2023 Day Two

day_two_2023.hs

{-# LANGUAGE OverloadedStrings #-}
module DayTwo
  ( partOne, greenCount, legalDraw, legalGame, partOneCheckRow, gameId, power, partTwo
  ) where

import qualified Data.Text as T
import qualified Data.List.Safe as LS
import qualified Data.Text.IO as TI


partOne :: IO ()
partOne = do
  fileBody <- TI.readFile "/home/me/Downloads/input.txt"
  let allLines = T.lines fileBody
      legalGames = filter partOneCheckRow allLines
      answer = sum $ map gameId legalGames
  print answer

partTwo :: IO ()
partTwo = do
  fileBody <- TI.readFile "/home/me/Downloads/input.txt"
  let allLines = T.lines fileBody
      answer = sum $ map power allLines
  print answer



maybeToInt :: (Maybe Int) -> Int
maybeToInt Nothing = 0
maybeToInt (Just n) = n

draws = T.split (== ';')

colorCount :: T.Text -> T.Text -> Int
colorCount target draw = maybeToInt asMaybe
  where splitted = T.split (== ' ') $ T.filter (/= ',') draw
        asMaybe = do
          colorIdx <- LS.elemIndex target splitted
          amountString <- splitted LS.!! (colorIdx - 1)
          return $ read $ T.unpack amountString

greenCount = colorCount "green"
blueCount = colorCount "blue"
redCount = colorCount "red"

minimumLegalColorCount color game = maximum $ map (colorCount color) $ draws game

minimumLegalGreenCount = minimumLegalColorCount "green"
minimumLegalRedCount = minimumLegalColorCount "red"
minimumLegalBlueCount = minimumLegalColorCount "blue"

power game = (minimumLegalGreenCount game) * (minimumLegalRedCount game) * (minimumLegalBlueCount game)

legalDraw maxRed maxGreen maxBlue draw = (greenCount draw <= maxGreen) && (redCount draw <= maxRed) && (blueCount draw <= maxBlue)

legalGame maxRed maxGreen maxBlue game = Prelude.all (legalDraw maxRed maxGreen maxBlue) (draws game)

partOneCheckRow = legalGame 12 13 14

gameId :: T.Text -> Integer
gameId game = read $ T.unpack $ splitted Prelude.!! 1
  where splitted = T.split (== ' ') noColons
        noColons = T.filter (/= ':') game