please give some usefull tests... thanx

which algo did you use? dp or greedy?
It's easy to find out usefull tests, you can do it by yourself :)

I use bruteforce with some optimizations... You can give me some tests?

can anybody help me?

Bruteforce, especially with optimizations, doesn't guarantee you right answer, so it is not astonishing that you got WA (this tells in favour of quality of tests).
Try to develop a DP solutiong to the problem.