AOC 2022 day 10 in Common Lisp, code golf style

aoc2022-day10.lisp

;;;; AOC 2022 day 10 in Common Lisp,
;;;; based on https://www.reddit.com/r/adventofcode/comments/zhjfo4/2022_day_10_solutions/izmspl7/

#| (mostly) original Python:

from itertools import accumulate

f = lambda x: int(x) if x[-1].isdigit() else 0
xs = [*map(f, open('day10.txt').read().split())]

part1, part2 = 0, '\n'
for i, x in enumerate(accumulate([1]+xs), 1):
    part1 += i*x if i%40==20 else 0
    part2 += '#' if ((i-1)%40)-x in [-1,0,1] else ' '
    if i%40 == 0:
        part2 += '\n'

print(part1, part2)

|#


(require "uiop")

(let* ((tokens (uiop:split-string (uiop:read-file-string "day10.txt") :separator '(#\Newline #\ )))
       (tokens (remove "" tokens :test 'equal))
       (xs (map 'list (lambda (x) (setq x (read-from-string x)) (if (numberp x) x 0)) tokens))
       (part1 0)
       (part2 (make-array 0 :element-type 'character :adjustable t :fill-pointer t))
       (i 1)
       (x 0))

  (vector-push-extend #\Newline part2)
  (push 1 xs)
  (dolist (n xs)
     (incf x n)
     (when (= (rem i 40) 20) (incf part1 (* i x)))
     (vector-push-extend (case (- (rem (- i 1) 40) x)
                               ((-1 0 1) #\#)
                               (t #\ ))
                         part2)
     (when (zerop (rem i 40))
       (vector-push-extend #\Newline part2))
     (incf i))

  (princ "AOC 2022 day10 part1: ") (princ part1) (terpri)
  (princ "AOC 2022 day10 part2: ") (princ part2))