OK, thanks for the notes - I think I got it now.
What confused me with your first attempt were quite a few things:
nested maps, that 1e3 trick, the freakish use of $. and especially that sick thing:
grep !$^H { $_ }++
Your current version is much straighter (not saying less tricky), and admittedly trailing zero suppression IS aesthetically more pleasing (shame on me!).

^~Django
"Why don't we ever challenge the spherical earth theory?"