day 5 part 1 in elisp

elisp/day-5/advent-of-code.el

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+../advent-of-code.el

elisp/day-5/example.txt

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+../../input/day-5-example.txt

elisp/day-5/input.txt

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+../../input/day-5.txt

elisp/day-5/solution.el

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+#!/usr/bin/env -S emacs --script
+
+;; -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2022 notroot
+
+;; 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 default-directory)
+
+(require 'cl-lib)
+(require 'eieio)
+(require 'ert)
+(require 'advent-of-code)
+
+(defmacro -make-crates (&rest exprs)
+  `(make-advent-of-code-day-5-crates ,@exprs))
+
+(cl-defstruct -crates
+  stacks)
+
+(defun -crates-pop (crates n)
+  (with-slots (stacks) crates
+    (when-let ((stack (assoc n stacks)))
+      (pop (cdr stack)))))
+
+(defun -crates-push (crates crate n)
+  (with-slots (stacks) crates
+    (if-let ((stack (assoc n stacks)))
+        (push crate (cdr stack))
+      (push (cons n (list crate)) stacks))))
+
+(defun -crates-append (crates crate n)
+  (with-slots (stacks) crates
+    (if-let ((stack (assoc n stacks)))
+        (setf (cdr stack) (append (cdr stack) (list crate)))
+      (push (cons n (list crate)) stacks))))
+
+(defun -crates-process-move (crates move)
+  (with-slots (n from to) move
+    (cl-loop repeat n
+             do (-crates-push crates (-crates-pop crates (- from 1)) (- to 1)))))
+
+(defun -crates-from-list (input)
+  (cl-loop for (crate . n) in input
+           with crates = (-make-crates :stacks nil)
+           do (-crates-append crates crate n)
+           finally (return crates)))
+
+(defmacro -make-move (&rest exprs)
+  `(make-advent-of-code-day-5-move ,@exprs))
+
+(cl-defstruct -move
+  n from to)
+
+(defun -parse-input-into-parts (input)
+  (let* ((delimiter (seq-position input "" 'string=))
+         (crates (seq-subseq input 0 (- delimiter 1)))
+         (moves (seq-subseq input (+ delimiter 1))))
+    (list crates moves)))
+
+(defun -parse-crates-from-line (line)
+  (cl-loop for i from 0 to (- (length line) 3) by 4
+           for n from 0
+           for crate = (substring line i (+ i 3))
+           for crate-id = (substring crate 1 2)
+           for empty? = (not (string-match-p "[^\s\n]" crate))
+           if (not empty?)
+           collect (cons crate-id n)))
+
+(defun -parse-move-from-line (line)
+  (save-match-data
+    (string-match (rx "move" space (group (one-or-more digit)) space
+                      "from" space (group (one-or-more digit)) space
+                      "to" space (group (one-or-more digit)))
+                  line)
+    (list (string-to-number (match-string 1 line))
+          (string-to-number (match-string 2 line))
+          (string-to-number (match-string 3 line)))))
+
+(defun -part-1 (input)
+  (pcase-let* ((`(,input-crates ,input-moves) (-parse-input-into-parts input))
+               (parsed-crates-list (cl-loop for line in input-crates
+                                            append (-parse-crates-from-line line)))
+               (crates (-crates-from-list parsed-crates-list))
+               (moves (cl-loop for line in input-moves
+                               for move = (pcase-let ((`(,n ,from ,to) (-parse-move-from-line line)))
+                                            (-make-move :n n :from from :to to))
+                               collect move)))
+    (seq-do (lambda (move)
+              (-crates-process-move crates move))
+            moves)
+    (cl-loop for n from 0 to (length (-crates-stacks crates))
+             for top-crate = (cadr (assoc n (-crates-stacks crates)))
+             for top-crates = top-crate then (concat top-crates top-crate)
+             finally (return top-crates))))
+
+(ert-deftest -test-part-1-example ()
+  (should (equal (-part-1 (aoc-read-file-lines "example.txt")) "CMZ")))
+
+(ert-deftest -test-part-1 ()
+  (should (equal (-part-1 (aoc-read-file-lines "input.txt")) "CFFHVVHNC")))
+
+(when noninteractive
+  (ert-run-tests-batch))
+
+;; Local Variables:
+;; read-symbol-shorthands: (("-" . "advent-of-code-day-5-") ("aoc-" . "advent-of-code-"))
+;; End: