!

You'd need a different set of currency for the greedy algorithm to fail. Try the sequal kata for something a little more challenging: https://www.codewars.com/kata/making-change-part-2

It's been in beta for years. :(

Great!

Could you please try again?

Which language?

Thanks for the hint. We will check this.

I was having the same issue until I read the directions again with a very fine-toothed comb. I skimmed past a word the first time and it threw off my algorithm :(

It's described in the docs at http://ruby-doc.org/core-2.2.3/String.html#method-i-gsub.

If the second argument is a Hash, and the matched text is one of its keys, the corresponding value is the replacement string.