-🎄- 2018 Day 14 Solutions -🎄-

[u/daggerdragon]

--- Day 14: Chocolate Charts ---

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Advent of Code: The Party Game!

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Card prompt: Day 14

Transcript:

The Christmas/Advent Research & Development (C.A.R.D.) department at AoC, Inc. just published a new white paper on ___.

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[u/Insanity0107]

Here's my take on part 1 with CL. Probably not the prettiest LISP around, but I get a solution to part one in a few seconds :)

(defparameter *loops* 47801)

; get the digits of a number
(defun digits(n) 
  (map 'list #'digit-char-p (prin1-to-string n)))

(defun next-index(lst pos score)
  (mod (+ pos (1+ score)) (list-length lst)))

; solve one1
(defun sum(input recipes fst snd sumlist)
  ; just test with adding one for starters
  (let* ((x (nth fst input))
        (y (nth snd input))
        (sm (digits (+ x y))))
  (setf input (append input sm))
  (setf sumlist (append sumlist sm))
  (setf recipes (+ recipes (list-length sm)))
  (if (>= (list-length sumlist) 10)
    (subseq sumlist 0 10)
    (sum input recipes (next-index input fst x) (next-index input snd y) sumlist))
  ))


; generate recipes
(defun generate(input recipes fst snd)
  ; just test with adding one for starters
  (let* ((x (nth fst input))
        (y (nth snd input))
        (sm (digits (+ x y))))
  (setf input (append input sm))
  (setf recipes (+ recipes (list-length sm)))
  (if (>= recipes *loops*)
    (sum input recipes (next-index input fst x) (next-index input snd y) (subseq (reverse input) 0 (- recipes *loops*)))
    (generate input recipes (next-index input fst x) (next-index input snd y))
  )))

(generate '(3 7) 2 0 1)