| 1 | (asdf:load-system :adventofcode2020) |
| 2 | (in-package #:adventofcode2020) |
| 3 | |
| 4 | (defun valid-password-count? (pw-spec) |
| 5 | (destructuring-bind (count-str char-str passwd) (split " " pw-spec) |
| 6 | (let ((countp (destructuring-bind (count-low count-high) (mapcar #'parse-integer (split "-" count-str)) |
| 7 | (lambda (n) |
| 8 | (<= count-low n count-high)))) |
| 9 | (char-count (loop with char = (char char-str 0) |
| 10 | for c across passwd |
| 11 | summing (if (char= c char) 1 0)))) |
| 12 | (funcall countp char-count)))) |
| 13 | |
| 14 | (defun valid-password-index? (pw-spec) |
| 15 | (destructuring-bind (index-str char-str passwd) (split " " pw-spec) |
| 16 | (let* ((indices (mapcar (compose #'1- #'parse-integer) (split "-" index-str))) |
| 17 | (char (char char-str 0)) |
| 18 | (get-char (lambda (n) (char passwd n)))) |
| 19 | (->> (mapcar get-char indices) |
| 20 | (remove char) |
| 21 | (length) |
| 22 | (= 1))))) |
| 23 | |
| 24 | (day 02 input |
| 25 | (let ((pws-and-specs (list-from input))) |
| 26 | (part1 (->> pws-and-specs |
| 27 | (remove-if-not #'valid-password-count?) |
| 28 | (length))) |
| 29 | (part2 (->> pws-and-specs |
| 30 | (remove-if-not #'valid-password-index?) |
| 31 | (length))))) |
| 32 | |
| 33 | (def-suite day02) |
| 34 | (in-suite day02) |
| 35 | |
| 36 | (test valid-password-count? |
| 37 | (is (equal |
| 38 | '(t nil t) |
| 39 | (mapcar #'valid-password-count? |
| 40 | '("1-3 a: abcde" "1-3 b: cdefg" "2-9 c: ccccccccc"))))) |
| 41 | |
| 42 | (test valid-password-index? |
| 43 | (is (equal |
| 44 | '(t nil nil) |
| 45 | (mapcar #'valid-password-index? |
| 46 | '("1-3 a: abcde" "1-3 b: cdefg" "2-9 c: ccccccccc"))))) |
| 47 | |
| 48 | (run! 'day02) |