Project Euler : Problem 38

dailycoding38.hs

-- Project Euler : Problem 38

import Data.List

isPandigital :: Maybe String -> Bool
isPandigital Nothing = False
isPandigital (Just x) = all (`elem` x) ['1'..'9']

catProduct :: Int -> Maybe String
catProduct x = find (\x -> (length x) == 9) $ map (product x) [2..9]
    where product x n = foldl (\acc y -> acc ++ y) "" $ map show $ map (* x) [1..n]

main = print $ last $ sort $ filter isPandigital $ map catProduct [1..9999]

-- Just "932718654"
-- ./dailycoding38  0.08s user 0.00s system 95% cpu 0.084 total