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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 like that it is short, but I cannot make it work on my system.
And you are right, it is a brute force solution, if I were going brute force, I would tend to use the built in permutations from Enumerable...