2011 08 19

prax-solution.hs

module Solution where

import List

solution :: String -> IO ()
solution a =
  case reduce a of
    [] -> putStrLn "No repeating characters!"
    (x:_) -> putStrLn $ "Solution: " ++ x
 where
   reduce = filter (\x -> length x == 1) . group . sort

Your code returns the alphabetically first non-repeating character, not the first according to the input string.

Example: For “fa” your code will give ‘a’, but the solution should give ‘f’.