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.
i guess it's to late but, in reduce, you have initial value after callback function, which is most of the times called accumulator. So if initial value is 0 and there is no elements in an array - it return 0, as callback never called.
No! The kata is correct check your code.