Incorrect answer for n=100: 10 should equal -1

So, the next smaller number from 100, isn't 010 (10)?

I don't get it.

Agree with Heptonius. There are better Katas out there, more examples, caveats to mention, etc.

This Kata can be an "existence stealer" counted in hours

It seems to me quite bad, to just leave a couple of silly examples on the description, when there are important details about other scenarios...

I celebrate the effort of bringing this Kata but sincerely, you can do better than this. You really can...

Didn't knew it was possible to create SP on Code Wars. Neat!

I could have used an easier way of doing this, but it wouldn't be so interesting...
Even though it's more code, I thing it's interesting to check next and previous elements, then returning the different element at once.

Just what I came up few seconds ago...

Maybe not the most efficient but, I mean, first passing all the tests, is what matters most :). Improving is another step though.

I've seen a solution using F strings, and it made me feel so dumb :')...