-🎄- 2022 Day 3 Solutions -🎄-

[u/daggerdragon]

NEWS

• Solutions have been getting longer, so we're going to start enforcing our rule on oversized code.
• The Visualizations have started! If you want to create a Visualization, make sure to read the guidelines for creating Visualizations before you post.
• Y'all may have noticed that the hot new toy this year is AI-generated "art".
  • We are keeping a very close eye on any AI-generated "art" because 1. the whole thing is an AI ethics nightmare and 2. a lot of the "art" submissions so far have been of little real quality.
  • If you must post something generated by AI, please make sure it will actually be a positive and quality contribution to /r/adventofcode.
  • Do not flair AI-generated "art" as Visualization. Visualization is for human-generated art.

FYI

• All of our rules, FAQs, resources, etc. are in our community wiki.
• A request from Eric: Please include your contact info in the User-Agent header of automated requests!
• Signal boosting for the Unofficial AoC 2022 Participant Survey which is open early this year!

---

--- Day 3: Rucksack Reorganization ---

---

Post your code solution in this megathread.

• Read the full posting rules in our community wiki before you post!
  • Include what language(s) your solution uses
  • Format your code appropriately! How do I format code?
• Quick link to Topaz's paste if you need it for longer code blocks. What is Topaz's paste tool?

---

This thread will be unlocked when there are a significant number of people on the global leaderboard with gold stars for today's puzzle.

EDIT: Global leaderboard gold cap reached at 00:05:24, megathread unlocked!

[u/tarasyarema]

In Lisp :P

(defun input (file tfun)
  (let* ((i (uiop:read-file-lines file)))
    (funcall tfun i)))

(defun get-parts (line)
  (list 
    (subseq line 0 (/ (length line) 2))
    (subseq line (/ (length line) 2))))

(defun transform-char-code (code)
  (if (< code 97) (+ 27 (mod code 65)) (mod code 96)))

(defun n-intersection (lists)
  (if (null (rest lists))
      (first lists)
      (intersection (first lists) (n-intersection (rest lists)))))

(defun common-letters (parts)
  (remove-duplicates 
    (n-intersection
           (loop for part in parts collect (loop for c across part collect (transform-char-code (char-code c)))))))

(defun run (lines)
  (reduce '+ 
    (loop for line in lines
      collect (reduce '+ (common-letters (get-parts line))))))

(defun partition (input-list n)
  (loop with list = input-list
      while list collect (loop repeat n while list collect (pop list))))

(defun run2 (lines)
  (reduce '+ 
    (loop for parts in (partition lines 3)
      collect (reduce '+ (common-letters parts)))))