Loading collection data...
Collections are a way for you to organize kata so that you can create your own training routines. Every collection you create is public and automatically sharable with other warriors. After you have added a few kata to a collection you and others can train on the kata contained within the collection.
Get started now by creating a new collection.
Would be nice to see bigger numbers, like 1 to 1000 for example
Also check for user solution length to avoid people using a pre-computed hashmap...
Trivial map/filter/reduce and factorial calculation are not novel kata ideas.
The name is a little misleading: maybe "product of factorials" instead of "factorial of factorials"? Not a huge deal, just a minor thing
You shoud put random test case and bigger number
About the random tests:
If you look at the link I gave you, you'll see that the idea is to generate a random input and to check the result of the user's function on it against the result of a reference solution. And you do that in a loop to do like 50-100 random tests.