Solution to Google Code Jam Q-B Cookie Cutter Alpha https://code.google.com/codejam/contest/2974486/dashboard#s=p1

cookie.hs

module Main where

import Control.Monad
import Numeric


-- https://code.google.com/codejam/contest/dashboard?c=2974486#s=p1
-- Input and output with standard redirection operators

-- Unless otherwise indicated, all modules used are either bundled with
-- the Haskell Platform (http://hackage.haskell.org/platform/) or available
-- as a separate download from Hackage (http://hackage.haskell.org/).

factoryTimes :: Double -> Double -> [Double]
factoryTimes c f = 0.0 : [ c / (2.0 + k * f) | k <- [0.0, 1.0 ..]]

productionTimes :: Double -> Double -> [Double]
productionTimes x f = [ x / (2.0 + k * f) | k <- [0.0, 1.0 ..]]

times :: Double -> Double -> Double -> [Double]
times c f x = zipWith (+) production factory
  where production = productionTimes x f
        factory = scanl1 (+) $ factoryTimes c f

firstMinimum :: [Double] -> Double
firstMinimum (x:y:ys) = if x < y
                        then x
                        else firstMinimum (y:ys)

solve :: Double -> Double -> Double -> Double
solve c f x = firstMinimum $ times c f x

main :: IO ()
main = do
  t <- getLine
  forM_ [1..read t :: Int] $ \i -> do
    [c, f, x] <- fmap (map read . words) getLine
    let result = solve c f x
    putStrLn $ concat ["Case #", show i, ": ", Numeric.showFFloat (Just 7) result ""]