aoc-2022/elisp/day-3/solution.el

84 lines
3.1 KiB
EmacsLisp
Executable file

#!/usr/bin/env -S emacs --script
;; -*- lexical-binding: t; -*-
;; Copyright (C) 2022
;; This program is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with this program. If not, see <https://www.gnu.org/licenses/>.
(add-to-list 'load-path "../")
(require 'ert)
(require 'advent-of-code)
(defvar solution-input
"../../input/day-3.txt")
(defvar solution-example-input
"../../input/day-3-example.txt")
(defun solution-letter-priority (char)
(if (char-uppercase-p char)
(+ (- char ?A) 26 1)
(+ (- char ?a) 1)))
(defun solution-3-way-intersection (a b c)
(seq-intersection (seq-intersection a b) c))
(defun solution-part-1 (input)
(let* ((char-lists (seq-map 'string-to-list input))
(split-into-halves (seq-map (lambda (char-list)
(seq-split char-list (/ (length char-list) 2)))
char-lists))
(common-items (seq-map (lambda (halves)
(if-let ((intersection (seq-intersection (car halves) (cadr halves))))
(car intersection)
nil))
split-into-halves))
(filter-nils (seq-filter (lambda (item)
(not (null item)))
common-items))
(item-priorities (seq-map 'solution-letter-priority common-items)))
(apply '+ item-priorities)))
(defun solution-part-2 (input)
(let* ((char-lists (seq-map 'string-to-list input))
(groups (seq-split char-lists 3))
(common-items (seq-map (lambda (group)
(car (seq-intersection (seq-intersection (car group)
(cadr group))
(caddr group))))
groups))
(item-priorites (seq-map 'solution-letter-priority common-items)))
(apply '+ item-priorites)))
(ert-deftest solution-part-1-example ()
(should (equal (solution-part-1 (aoc-read-file-lines solution-example-input)) 157)))
(ert-deftest solution-part-1 ()
(should (equal (solution-part-1 (aoc-read-file-lines solution-input)) 7878)))
(ert-deftest solution-part-2-example ()
(should (equal (solution-part-2 (aoc-read-file-lines solution-example-input)) 70)))
(ert-deftest solution-part-2 ()
(should (equal (solution-part-2 (aoc-read-file-lines solution-input)) 2760)))
(when noninteractive
(ert-run-tests-batch))
;; Local Variables:
;; read-symbol-shorthands: (("solution-" . "advent-of-code-day-3-") ("aoc-" . "advent-of-code-"))
;; End: