OP solved it, closing

Well, the first mistake is not formatting the posted code ;) Please see this for help: https://docs.codewars.com/references/markdown#code-block

Maybe use number of combinations and letters in word =)

what did you use instead of your eyes?

same same same. done. did not use eyes when was reading statement

same problem

The kata expects that you don't create a new array (String[] result in your case), but you modify in place the array that you receive as a parameter.

That is a problem with your code, not a kata issue. Read the error message, rethink the order you use to do things in your code.

Do you mean that you are timing out ?

Then this is normal - your current solution is very slow for large input numbers like 1000000000.

You need to find a faster approach to pass all the tests.