>At the same time I knew that the final step had to involve 3 coins or less
Except that's not true.
>Brute force is a strategy
I don't know of anyone who has ever solved this with brute force, how hard could it be with Python?
>I would say that you used some other guide other than just a decision tree.
I think my memory is essentially accurate. I noticed the "form of the logical statements" one could make, and sought to find weighings down the B1 & B2 paths that gave the same form as the A path I had already solved. Somehow I had an inspiration to "mix up" the balls for the second weighing. I wasn't really thinking of sports (I was joking).