U = unknown
R = confirmed regular BB
H = potentially heavy BB
L = potentially light BB
HHU RRR = two H's and a U on one balance, three R's on the other...
I'm with you through the end of the second weighing.
1 = UUUUUU UUUUUU (gives you HHHHHH LLLLLL after weighing)
2 = HHH LLL
so regardless of if weighing 2 is even or uneven, you can assign HHH, LLL, and RRRRRR.
How does weighing 3 locate the BB out of the 3 H's and 3 L's?