Sorry, this is not 'best practices' in Ruby. This looks like the way you'd do it in another language, translated to Ruby.

I was trying to get to this! I knew there had to be a one-liner with take_while. I didn't quite achieve it. Well done.

Did this one throw you a bit? ;)

Nice. I'd forgotten about the replacement-hash form of gsub.

LOL to those who voted 'Best Practices'. This is NOT a best practice. I used it because I didn't think about the safer fetch which is superior.

Kinda threw that rescue in there, had one case failing LOL

Convoluted, but I like it :)

This is my favorite answer. Everything is simplified as much as possible without sacrificing the readability of the variable names. Well done.

This solution seems to assume you can't refactor the Node class.

Beautiful!

This method was created for this kata. Probably the only time it's ever been used LOL

No, I did that and it passed all tests. I'm a bit disappointed that there wasn't a test that invalidated the answers which didn't add your points.

This one's my favorite. Very concise and readable. Nice

I think you wanted

(0..9).include? a