This was fun, it reminded me of when we had to build a regular expression parser in college. I did find it relatively much easier than the only other 2 kyu one I've solved ("Assorted Rectangular Pieces Puzzle"). But I suppose difficulty varies a lot based on exposure to similar problems.

This is amazing

Very fun and challenging kata! It took me about 9 days to solve, but I learned a lot.

Thank you!

Clarification needed for single character strings. Expected output is 1. Why? The description asks for the smallest possible number. 0 is less than 1, so surely it should be 0. I guess negative numbers not being allowed is implied.

Problem description should clarify that the output should be smallest possible number, greater than 0. And/or perhaps change single char cases to be 0, that makes more sense to me.

(I know I told you already, just posting in here to keep track of the issues :) )