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;;; solver.el --- Day 07 -*- lexical-binding: t; -*-
;;
;; Copyright (C) 2022 Óscar Nájera
;;
;; Author: Óscar Nájera <hi@oscarnajera.com>
;; Maintainer: Óscar Nájera <hi@oscarnajera.com>
;; Created: December 08, 2022
;; Modified: December 08, 2022
;;
;; This file is not part of GNU Emacs.
;;
;;; Commentary:
;;
;; Day 07
;;
;;; Code:
(require 'cl-lib)
(insert "$ cd /
$ ls
dir a
14848514 b.txt
8504156 c.dat
dir d
$ cd a
$ ls
dir e
29116 f
2557 g
62596 h.lst
$ cd e
$ ls
584 i
$ cd ..
$ cd ..
$ cd d
$ ls
4060174 j
8033020 d.log
5626152 d.ext
7214296 k")
(with-temp-buffer
(insert-file-contents "input")
(solver-add-dir-size
(solver-parse-listing (split-string (buffer-string) "\n"))))
(defun solver-parse-listing (lines)
(cl-labels ((scan ()
(cl-loop for item = (pop lines)
while (and item (not (string= "$ cd .." item)))
when (parse item)
collect it))
(parse (entry)
(pcase (split-string entry)
(`("$" "cd" ,dir) (cons dir (scan)))
(`("$" "ls") nil)
(`("dir" ,dir) nil)
(`(,size ,name) (cons name (string-to-number size))))))
(car (scan))))
(defun solver-add-dir-size (tree)
(cl-labels ((combiner (tri)
(list (car tri)
(adder tri)
(seq-reduce (lambda (acc item)
(if (numberp (cdr item))
acc
(cons (combiner item) acc)))
(cdr tri) nil)))
(adder (tri)
(seq-reduce (lambda (acc item)
(+ acc
(if (numberp (cdr item))
(cdr item)
(adder item))))
(cdr tri) 0)))
(cl-loop for (_ size) on (flatten-tree (combiner tree)) by #'cddr
when (< size 100000)
sum size)))
(provide 'solver)
;;; solver.el ends here
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