Java&Sepples Challenge

Okay, here is the challenge.
The first one after me creates a very easy problem. The first person to post a working solution to that problem with either Java or C++ posts another problem but this time slightly more difficult then the previous and so on.

import Data.List (delete)

combinations [] = [[]]
combinations (x:xs) = map (x:) xs' ++ xs'
  where xs' = combinations xs

subsetsum n = any ((== n) . sum) . delete [] . combinations