advent09.hs

   1 module Main(main) where
   2
   3 import Data.List.Split (splitOn)
   4 import Data.Char (isSpace)
   5
   6 type Chunk = (Int, String)
   7
   8 main :: IO ()
   9 main = do
  10         textL <- readFile "advent09.txt"
  11         let text = filter (not . isSpace) textL
  12         part1 text
  13         part2 text
  14
  15 part1 :: String -> IO ()
  16 part1 text = do
  17     print $ cLength $ decompress text
  18
  19 part2 :: String -> IO ()
  20 part2 text = do
  21     print $ cLength $ decompress2 text
  22
  23
  24 decompress :: String -> [Chunk]
  25 decompress text =
  26     if not (null msuf)
  27         then (1, pre):(num, chunk):drest
  28         else [(1, pre)]
  29     where
  30         (pre, msuf) = span ('(' /= ) text
  31         (marker, suf) = span (')' /= ) msuf
  32         ln = splitOn "x" (tail marker)
  33         len = read (ln!!0) :: Int
  34         num = read (ln!!1) :: Int
  35         (chunk, remainder) = splitAt len (tail suf)
  36         drest = decompress remainder
  37
  38 decompress2 :: String -> [Chunk]
  39 decompress2 text =
  40     if not (null msuf)
  41         then [(1, pre)] ++ mulDchunks ++ drest
  42         else [(1, pre)]
  43     where
  44         (pre, msuf) = span ('(' /= ) text
  45         (marker, suf) = span (')' /= ) msuf
  46         ln = splitOn "x" (tail marker)
  47         len = read (ln!!0) :: Int
  48         num = read (ln!!1) :: Int
  49         (chunk, remainder) = splitAt len (tail suf)
  50         dchunks = decompress2 chunk
  51         mulDchunks = [(dl * num, ds) | (dl, ds) <- dchunks]
  52         drest = decompress2 remainder
  53
  54 cLength :: [Chunk] -> Int
  55 cLength = sum . map (clen)
  56     where clen (n, t) = n * (length t)
  57