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2.1 KiB
2.1 KiB
Solution to p4
Yay, a maze. Cool. No, not cool.
(with-temp-buffer
(insert-file-contents "input")
(advent/replace-multiple-regex-buffer
'(("^\\(.*\\)$" . "\"\\1\" ")))
(goto-char (point-min))
(insert "(setq data '(")
(goto-char (point-max))
(insert "))")
(eval-buffer))
(setq data-char (-map #'advent/split-string-into-char-list data)
width (length (car data-char))
height (length data-char))This is for part 1; easy
(defun position-valid-p (pos)
(and (and (>= (car pos) 0) (< (car pos) width))
(and (>= (cadr pos) 0) (< (cadr pos) height))))
(defun roll-at-p (pos data-char)
(when (position-valid-p pos)
(eq ?@ (advent/char-at pos data-char))))
(setq adjacent '((-1 -1)
(-1 0)
(-1 1)
(0 1)
(0 -1)
(1 -1)
(1 0)
(1 1)))
(defun rolls-adjacent (pos data-char)
(length (-non-nil (--map (roll-at-p it data-char) (--map (advent/neighbour pos it) adjacent)))))
(length (--filter (< it 4)
(--map (rolls-adjacent it data-char) (advent/coordinates-of ?@ data-char))))1464
Now for part two, we create a new data-char at each removal step I am not particularly happy style-wise, but that is it for today
(defun tensor (a b)
(-map (lambda (x) (--map (list it x) a)) b))
(setq initial-roll-number (length (advent/coordinates-of ?@ data-char))
current-roll-number (1+ initial-roll-number))
(while (> current-roll-number
(setq current-roll-number (length (advent/coordinates-of ?@ data-char))))
(setq data-char
(-map (lambda (row)
(--map (if (and (= ?@ (advent/char-at it data-char))
(<= 4 (rolls-adjacent it data-char)))
?@ ?.)
row))
(tensor (-iterate #'1+ 0 width)
(-iterate #'1+ 0 height)))))
(- initial-roll-number current-roll-number)8409