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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.
my first implementation is similar to yours. but the performance is too bad... what is your magic? ;)
very clever solution!
I got a question about
s == e, does it mean that one could go from 'a' to 'a' even 'a' is not in the graph?This comment is hidden because it contains spoiler information about the solution
I thinks this kata is the same as http://www.codewars.com/kata/53daa9e5af55c184db00025f.
Should Consider the situation of input is None.