advent-2024/p17/p17.org

solution to p17

Load program

  (require 'dash)

  (defun replace-regexp-from-top (a b)
    (goto-char (point-min))
    (replace-regexp a b))

    (with-temp-buffer
      (insert-file-contents "input")
      (replace-regexp-from-top "Register \\(.\\): \\(.*\\)$" "(setq \\1 \\2)")

      (replace-regexp-from-top "\\(.\\),\\(.\\)" "(\\1 \\2)")
      (replace-regexp-from-top "," " ")
      (replace-regexp-from-top "Program: \\(.*\\)$" "(setq program '(\\1))")


      (eval-buffer))

  (let ((opcode-alist '( (0 . adv)
			 (1 . bxl)
			 (2 . bst)
			 (3 . jnz)
			 (4 . bxc)
			 (5 . out)
			 (6 . bdv)
			 (7 . cdv))))
    (setq proggo (--map (cons (cdr (assoc (car it) opcode-alist)) (cdr it)) program)))

bst	4
bxl	5
cdv	5
bxl	6
adv	3
bxc	1
out	5
jnz	0

  (defun combo (c)
    (let ((combo-alist `( (4 . ,A)
			  (5 . ,B)
			  (6 . ,C))))
      (if (< c 4) c
	(cdr (assoc c combo-alist)))))

  (defun aux-adv (c)
    (/ A (expt 2 (combo c))))

  (defun adv (c)
    (setq A (aux-adv c)))

  (defun bdv (c)
    (setq B (aux-adv c)))

  (defun cdv (c)
    (setq C (aux-adv c)))

  (defun bxl (l)
    (setq B (logxor l B)))

  (defun bst (c)
    (setq B (mod (combo c) 8)))

  (defun out (c)
    (let ((out-c (mod (combo c) 8)))
      (print out-c)
      (if so (setq so (concat so (format ",%d" out-c)))
	(setq so (format "%d" out-c))
	)))

  (defun bxc (l)
    (setq B (logxor B C)))

  (defun jnz (l)
    (unless (eq A 0)
      (setq ip (- (/ l 2) 1))))


  (defun exec (pr)
    (setq so nil
	  ip 0
	  stack-trace nil)

    (while (nth ip pr)
      (push (list A B C ip (nth ip pr)) stack-trace)
      (eval (nth ip pr))
      (setq ip (1+ ip)))
    so
    )

					  ;boot
  (exec proggo)
  stack-trace

0	1	0	7	(jnz 0)
0	1	0	6	(out 5)
0	1	0	5	(bxc 1)
2	1	0	4	(adv 3)
2	7	0	3	(bxl 6)
2	7	21	2	(cdv 5)
2	2	21	1	(bxl 5)
2	19	21	0	(bst 4)
2	19	21	7	(jnz 0)
2	19	21	6	(out 5)
2	6	21	5	(bxc 1)
21	6	21	4	(adv 3)
21	0	21	3	(bxl 6)
21	0	10	2	(cdv 5)
21	5	10	1	(bxl 5)
21	8	10	0	(bst 4)
21	8	10	7	(jnz 0)
21	8	10	6	(out 5)
21	2	10	5	(bxc 1)
169	2	10	4	(adv 3)
169	4	10	3	(bxl 6)
169	4	10	2	(cdv 5)
169	1	10	1	(bxl 5)
169	11	10	0	(bst 4)
169	11	10	7	(jnz 0)
169	11	10	6	(out 5)
169	1	10	5	(bxc 1)
1354	1	10	4	(adv 3)
1354	7	10	3	(bxl 6)
1354	7	677	2	(cdv 5)
1354	2	677	1	(bxl 5)
1354	679	677	0	(bst 4)
1354	679	677	7	(jnz 0)
1354	679	677	6	(out 5)
1354	2	677	5	(bxc 1)
10833	2	677	4	(adv 3)
10833	4	677	3	(bxl 6)
10833	4	86669	2	(cdv 5)
10833	1	86669	1	(bxl 5)
10833	86667	86669	0	(bst 4)
10833	86667	86669	7	(jnz 0)
10833	86667	86669	6	(out 5)
10833	6	86669	5	(bxc 1)
86669	6	86669	4	(adv 3)
86669	0	86669	3	(bxl 6)
86669	0	21667	2	(cdv 5)
86669	5	21667	1	(bxl 5)
86669	21664	21667	0	(bst 4)
86669	21664	21667	7	(jnz 0)
86669	21664	21667	6	(out 5)
86669	3	21667	5	(bxc 1)
693352	3	21667	4	(adv 3)
693352	5	21667	3	(bxl 6)
693352	5	86669	2	(cdv 5)
693352	0	86669	1	(bxl 5)
693352	86669	86669	0	(bst 4)
693352	86669	86669	7	(jnz 0)
693352	86669	86669	6	(out 5)
693352	0	86669	5	(bxc 1)
5546819	0	86669	4	(adv 3)
5546819	6	86669	3	(bxl 6)
5546819	6	22187278	2	(cdv 5)
5546819	3	22187278	1	(bxl 5)
5546819	22187273	22187278	0	(bst 4)
5546819	22187273	22187278	7	(jnz 0)
5546819	22187273	22187278	6	(out 5)
5546819	7	22187278	5	(bxc 1)
44374556	7	22187278	4	(adv 3)
44374556	1	22187278	3	(bxl 6)
44374556	1	0	2	(cdv 5)
44374556	4	0	1	(bxl 5)
44374556	0	0	0	(bst 4)

  stack-trace

1

44374556	nil	0	2	(cdv 5)
44374556	4	0	1	(bxl 5)
44374556	0	0	0	(bst 4)

so "1,0,4,6,7,3,5,2,1,0" (setq A 739) (combo 4) (adv 1) (/ A (expt 2 (combo 5))) stack-trace ((0 0 0 2 (jnz 0)) (0 0 0 1 (out 4)) (1 0 0 0 (adv 1)) (1 0 0 2 (jnz 0)) (1 0 0 1 (out 4)) (2 0 0 0 (adv 1)) (2 0 0 2 (jnz 0)) (2 0 0 1 (out 4)) (5 0 0 0 (adv 1)) (5 0 0 2 (jnz 0)) (5 0 0 1 (out 4)) (11 0 0 0 (adv 1)) …) so "1,1,1,1,1,1,1,1,1,1"