Populating variables based on button states

I was able to get the simple case working, with no ability to "unselect" a value. It is a lot of triggers and a lot of typing, even for my proof-of-concept with only 5 buttons and 3 selections.

My triggers with just 3 options look like this, but you'll need 10 triggers for each button:

With each subsequent choice, you continue the pattern of

    A) Checking that the previous choice has been filled out

    B) Checking that the clicked button has not already been used, and

    C) Checking that the choice is not already filled out.

(B) requires an additional condition for each choice, so the 10th choice would require 9 conditions to check if it's been used in any of the 9 prior choices.

I also have a Javascript solution here, and I'm working on a blog post with an in-depth explanation of each!