第11回 オフラインリアルタイムどう書くに行ってきました

第11回 オフラインリアルタイムどう書くで出題された問題の回答です。
会場で書いたそのままです。55分くらいでどうにか。

dokaku.hs

module Main where

import Data.Bits (shift, (.&.))
import Data.List (groupBy)
import Numeric (readHex)
import Test.HUnit (Test(..), runTestTT, (~=?))

type Problem = [Row]
type Row = [(Int, Int)]
type Columns = [Column]
type Column = Int

initState :: Columns
initState = [0..8]

main :: IO ()
main = print =<< runTestTT (TestList $ map toTest testdata)

solve :: String -> String
solve = writeProblem . foldl go initState . readProblem

readProblem :: String -> Problem
readProblem = map toRow . break'

break' :: String -> [String]
break' "" = []
break' s = case break (== '-') s of
  (x, '-':y) -> x : break' y
  (x, y) -> x : break' y

toRow :: String -> Row
toRow = map (\l -> (fst $ head l, succ $ fst $ last l)) . filter (snd . head) . groupBy (\x y -> snd x == snd y) . zip [0..] . toRow'

toRow' :: String -> [Bool]
toRow' s = map (\m -> (fst (head $ readHex s) .&. m) /= (0 :: Int)) masks
  where
    masks = map (shift 1) [7,6..0]

go :: Columns -> Row -> Columns
go c r = foldl go' c r

go' :: Columns -> (Int, Int) -> Columns
go' c (x, y) = map f $ zip [0..] c
  where
    f (i, n) | i == x = c !! y
             | i == y = c !! x
             | otherwise = n

writeProblem :: Columns -> String
writeProblem = concat . map show

---- unit testing

toTest :: (String, String) -> Test
toTest (input, expected) = expected ~=? solve input

testdata :: [(String, String)]
testdata =
  [ ( "d6-7b-e1-9e", "740631825" )
  , ( "83-4c-20-10", "123805476" )
  , ( "fb-f7-7e-df", "274056813" )
  , ( "55-33-0f-ff", "123456780" )
  , ( "00-00-00-00", "012345678" )
  , ( "00-00-00-55", "021436587" )
  , ( "40-10-04-01", "021436587" )
  , ( "00-00-aa-00", "103254768" )
  , ( "80-20-08-02", "103254768" )
  , ( "ff-7e-3c-18", "876543210" )
  , ( "aa-55-aa-55", "351708264" )
  , ( "55-aa-aa-55", "012345678" )
  , ( "db-24-db-e7", "812543670" )
  , ( "00-01-00-40", "021345687" )
  , ( "00-00-80-00", "102345678" )
  , ( "01-40-00-00", "021345687" )
  , ( "00-00-00-02", "012345768" )
  , ( "00-00-02-00", "012345768" )
  , ( "00-14-00-00", "012436578" )
  , ( "00-00-01-40", "021345687" )
  , ( "00-80-01-00", "102345687" )
  , ( "c8-00-00-81", "120354687" )
  , ( "05-48-08-14", "021435687" )
  , ( "24-05-00-f0", "413205687" )
  , ( "40-08-14-01", "021536487" )
  , ( "18-c8-80-80", "210534678" )
  , ( "1c-88-52-00", "120564738" )
  , ( "ec-dc-67-62", "213468705" )
  , ( "0a-b6-60-e9", "035162784" )
  , ( "52-d6-c6-c2", "120345678" )
  , ( "47-e7-b0-36", "231047658" )
  , ( "0f-85-91-aa", "108263754" )
  , ( "76-b6-ed-f3", "601435782" )
  , ( "f5-5e-f7-3d", "025847163" )
  , ( "dd-e7-fb-f9", "610247538" )
  , ( "8f-f4-af-fd", "583246017" )
  , ( "bf-fb-cb-f7", "105382674" )
  , ( "e5-fd-ff-ff", "512046378" )
  , ( "ef-df-ef-fe", "713205648" )
  , ( "bf-7f-fd-d7", "826437105" )
  , ( "36-ff-df-de", "814527603" )
  , ( "6f-dd-ff-ff", "230685147" )
  ]