SnapperChain.hs

stateString :: Int -> Bool -> String
stateString i False = "Case #" ++ show i ++ ": OFF"
stateString i True = "Case #" ++ show i ++ ": ON"

isOn :: Int -> Int -> Bool
isOn snappers snaps = isInt ((fromIntegral (snaps + 1) :: Double) / (fromIntegral (2^snappers) :: Double))
                        where isInt :: Double -> Bool
                              isInt d = (d - fromIntegral (floor d) :: Double) == 0

readInput :: String -> [(Int, Int)]
readInput input = map arrayToIntegerTuple $ tail $ map words $ lines input
                    where arrayToIntegerTuple :: [String] -> (Int, Int)
                          arrayToIntegerTuple [x, y] = (stringToInteger x, stringToInteger y)
                          stringToInteger :: String -> Int
                          stringToInteger s = read s

generateOutput :: [(Int, Int)] -> String
generateOutput input = unlines $ outputString input 1
                        where outputString :: [(Int, Int)] -> Int -> [String]
                              outputString (x:xs) i = (stateString i (isOn (fst x) (snd x))):(outputString xs (i + 1))
                              outputString [] i = []

main = do
  input <- readFile "large.txt"
  writeFile "output.txt" (generateOutput (readInput input))