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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.
And also can solving using the getCandidates, which is more efficient (O(nlog n), backtracking has O(9^nn)
You don't have to do backtracking, you can solve it with a direct algorithm.
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