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(ns org.vuxu.aoc2021.day16
(:require [clojure.string :as str]
[clojure.pprint :refer [cl-format]]))
(defn hex2bin [hex]
(map #(Character/digit % 2)
(mapcat #(cl-format nil "~4,'0B" (Character/digit % 16)) hex)))
(defn bin2int [bin]
(Integer/parseInt (apply str bin) 2))
(def data
(->> (slurp "day16")
str/trim-newline
hex2bin))
(declare parse-all)
(declare parse-n)
(defn parse [bin]
(let [[version bin] (split-at 3 bin)
[type bin] (split-at 3 bin)
version (bin2int version)
type (bin2int type)
[content bin] (if (= type 4)
(loop [bin bin
lit 0]
(let [[cont bin] (split-at 1 bin)
[data bin] (split-at 4 bin)
lit (bit-or (bit-shift-left lit 4)
(bin2int data))]
(if (= cont [1])
(recur bin lit)
[{:literal lit} bin])))
(let [[length-type bin] (split-at 1 bin)
[inner-packets bin]
(if (= length-type [0])
(let [[l bin] (split-at 15 bin)
[packets bin]
(split-at (bin2int l) bin)]
[(parse-all packets) bin])
(let [[n bin] (split-at 11 bin)]
(parse-n bin (bin2int n))))
]
[{:operator inner-packets} bin]))
]
[(into {:version version :type type} content)
bin]))
(defn parse-all [bin]
(loop [bin bin
parsed []]
(if (seq bin)
(let [[item bin] (parse bin)]
(recur bin (conj parsed item)))
parsed)))
(defn parse-n [bin n]
(loop [bin bin
n n
parsed []]
(if (zero? n)
[parsed bin]
(let [[item bin] (parse bin)]
(recur bin (dec n) (conj parsed item))))))
(defn sum-version [packet]
(if (:literal packet)
(:version packet)
(+ (:version packet)
(apply + (map sum-version (:operator packet))))))
(def part1
(sum-version (first (parse data))))
;; => 981
(defn eval-packet [packet]
(prn packet)
(case (:type packet)
0 (apply + (map eval-packet (:operator packet)))
1 (apply * (map eval-packet (:operator packet)))
2 (apply min (map eval-packet (:operator packet)))
3 (apply max (map eval-packet (:operator packet)))
4 (:literal packet)
5 (if (> (eval-packet (first (:operator packet)))
(eval-packet (second (:operator packet))))
1
0)
6 (if (< (eval-packet (first (:operator packet)))
(eval-packet (second (:operator packet))))
1
0)
7 (if (= (eval-packet (first (:operator packet)))
(eval-packet (second (:operator packet))))
1
0)))
(def part2
(eval-packet (first (parse data))))
;; => 299227024091
|
