AoC 2024, day 1, part 2 (dc)

# Command: dc -fdc-p2.dc <input

0 Sa                # bottom sentinel of stack a

# Read Input
?
[
    # stack: item2  item1
    d;b 1+ r:b      # b(item2)++
    Sa              # push item1 on stack a
    ? z0<I
] dsIx

# Process
0La                   # sum
[
    d;b *+          # sum += b(item) * item
    La d0<L
] dsLx

[Part 2: ]nrp