src/adventofcode2019/day08.clj

   1 (ns adventofcode2019.day08
   2     [:require [adventofcode2019.lib :refer :all]
   3               [clojure.core.match :refer [match]]])
   4
   5 (def combine-layers
   6   "Binary operation on the pixels of two layers, the first above the second."
   7   #(match [%1 %2]
   8           [0 _] 0
   9           [1 _] 1
  10           [2 p] p))
  11
  12 (defn day08 []
  13   (let [input (mapv parse-int (get-list-from-file (input-file) #""))
  14         layer-size (* 25 6)
  15         count-num #(count (filter (hash-set %1) %2))
  16         layers (partition layer-size input)
  17         fewest-zeroes (apply (partial min-key (partial count-num 0))
  18                              layers)
  19         layered-image (reduce #(mapv combine-layers %1 %2) layers)
  20         to-ascii #(match % 0 \u0020 ; 0s are spaces, 1s are full-block
  21                            1 \u2588)]
  22     (part1 (* (count-num 1 fewest-zeroes)
  23               (count-num 2 fewest-zeroes)))
  24     (part2 "see below")
  25     (run! println (partition 25 (map to-ascii layered-image)))))