AoC 2025, day 5 part 1 (dc)

# Command: tr '-' ' ' </tmp/input | dc -fdc-p1.dc

# read ranges section onto stack
0 ?             # end start i
[
    3R d3R r:r  # range(i)   = end;   i start
    1+ d3R r:r  # range(++i) = start; i
    1+ ? z1<L
] dsLx          # length of range array left on stack

[ lc1+sc q ] sC

# count food ids that fall in a range
?
[
    sf d                    # i=num | num (length of array)
    [
          1- d;r lf-        # end-food i
        r 1- d;r lf-        # start-food i end-food
        3R*                 # (start-food)*(end-food) i
        0!<C                # if test <= 0 then count and quit
        d0<I
    ] dsIx s.

    ? z1<M
] dsMx

[Part 1: ]n lcp