Bank Algorithm: part 2 (continued)
option 1: check classes in decreasing balance order
      let b_ij = min(B_ij, h), where h is a
           relatively small #
        R_ij += b_ij, and draw b_ij from j's
           bank account
        t_i  += b_ij
      until t_i >= T_i
option 2: check all classes in case 4 above with balance >= 0
allocate T_i - t_i tickets to these classes
proportional to their bank account, and draw
from bank account accordingly