advent08/src/advent08.hs

   1 import Data.List
   2 import Data.List.Split
   3 import Data.Char
   4 import Data.Ord
   5
   6 main :: IO ()
   7 main = do
   8         text <- readFile "data/advent08.txt"
   9         let digits = successfulParse text
  10         let layers = chunksOf (imageWidth * imageHeight) digits
  11         print $ part1 layers
  12         putStrLn $ part2 layers
  13
  14 imageWidth = 25
  15 imageHeight = 6
  16
  17 part1 layers = (count 1 target) * (count 2 target)
  18     where target = minimumBy (comparing (count 0)) layers
  19
  20 part2 layers = unlines rows
  21     where pixelLayers = transpose layers
  22           pixels = map firstVisible pixelLayers
  23           image = concatMap showPixel pixels
  24           rows = chunksOf imageWidth image
  25
  26 firstVisible = head . dropWhile (== 2)
  27
  28 showPixel 0 = " "
  29 showPixel 1 = "\x2588"
  30
  31 count n = length . filter (== n)
  32
  33 successfulParse :: String -> [Int]
  34 successfulParse input = map digitToInt input