AoC 2023 day 18, part 2 (dc)

# Command: perl -pe's/.*([0-9a-f]{6})./\U$1/' input | dc -fpart2.dc

# ASSUME: Every line is a 90 degree turn (just swap x and y on the stack each time)
16i                             # hexadecimal input
0d ?                            # y x colour
[
    10~                         # y x len dir
    2~                          # y x len upleft=dir/2 vert=dir%2
    2*1- r2*1-                  # y x len vert=(1|-1) upleft=(1|-1)
    3Rd lb+sb *                 # border += len; y x vert delta=upleft*len

    d 4R+ _4R                   # x+=delta y vert delta
    *r d3R *                    # x y vert*delta*y
    la+sa                       # area += vert * delta * y; x y

    ? z2<M
] dsMx

[Part 2: ]n lad*v lb+ 2/ 1+p