gistfile1.hs

import Control.Applicative ((<$>))
import Data.Function (on)
import Data.List (find, nubBy)
import Data.List.Utils (split)
import Data.Maybe (fromMaybe)
import Data.Ord (comparing)
import System.Environment (getArgs)
import System.IO (stdin, hGetContents, openFile, IOMode(ReadMode))

data SetOp = SetRow { row :: Int, val :: Int } | SetCol { col :: Int, val :: Int }

isSetRow (SetRow _ _) = True
isSetRow _ = False

isSetCol (SetCol _ _) = True
isSetCol _ = False

index (SetRow r _) = r
index (SetCol c _) = c

query isSetAll isSetOne ops which =
    let base = fromMaybe 0 $ val <$> find (isSetAll which) ops
        cols = nubBy (on (==) index) . filter isSetOne . takeWhile (not . isSetAll which) $ ops
    in base * (256 - length cols) + sum (map val cols)

queryRow = query (\r -> \op -> isSetRow op && row op == r) isSetCol
queryCol = query (\c -> \op -> isSetCol op && col op == c) isSetRow

process = reverse . fst . foldl f ([],[]) . lines
    where f (res, acc) cmd =
            case split " " cmd of
                "SetRow" : row : val : [] -> (res, SetRow (read row) (read val) : acc)
                "SetCol" : col : val : [] -> (res, SetCol (read col) (read val) : acc)
                "QueryRow" : row : [] -> (queryRow acc (read row) : res, acc)
                "QueryCol" : col : [] -> (queryCol acc (read col) : res, acc)
                _ -> error "Invalid command"

main = getArgs >>= getHandle >>= hGetContents >>= (mapM_ print . process)
    where getHandle args = if null args then return stdin else openFile (head args) ReadMode