src/adventofcode2019/day16.clj

   1 (ns adventofcode2019.day16
   2   [:require [adventofcode2019.lib :refer :all]
   3    [clojure.string :as str]])
   4
   5 (defn parse-input [input]
   6   (map (comp parse-int str) input))
   7
   8 (defn phase [input]
   9   (let [pattern (fn [n]
  10                   (->> [0 1 0 -1]
  11                        (mapcat (partial repeat n))
  12                        (cycle)
  13                        (rest)))
  14         transform (fn [i n]
  15                     (->> (map * input (pattern (inc i)))
  16                          (reduce +)
  17                          (str)
  18                          (last)
  19                          (str)
  20                          (parse-int)))]
  21     (map-indexed transform input)))
  22
  23 (defn result-of [input]
  24   (as-> (parse-input input) it
  25         (iterate phase it)
  26         (nth it 100)
  27         (take 8 it)
  28         (str/join it)))
  29
  30 (defn day16 []
  31   (let [[input] (get-list-from-file (input-file))]
  32     (part1 (result-of input))
  33     #_(part2)))