[LANGUAGE: Python3]

First solution this year I've been happy with enough to post.

Approach is similar to what other posters have used. Recursively build a tree to reach all of the A nodes, keeping track of criteria used to reach the A node along the way. The big thing that got me was as you slide across the criteria, you have to also keep the inversion of that criteria because it didn't match.

After you have the criteria its as easy as throwing out the possibilities that don't match. Then just do a multiplicative sum of the ranges left.

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