AoC day 21 part 1 (dc)

#!/usr/bin/dc

1:p 0:p                         # starting positions

0dsp sr                         # set player and roll to zero

[ lrd100%r1+sr ] SR             # put die roll on stack while updating r
[ lRddxrx+rx+3+ ] SS            # roll three times and sum

[
    lSx                         # roll

    lp;p+1-10%1+ dlp:p          # (p(p) = (p(p) + roll - 1) % 10 + 1) new-p(p) on stack
    lp;s + dlp:s                # (s(p) = (s(p) + new p(p))) new-s(p) on stack

    lp1r-sp                     # toggle player
    1000>L                      # loop if new-s(p) < 1000
] SL
lLx

[Part 1: ]n lp;s lr*p