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(require '[clojure.string :as str])
(defn pad-input-map [in-map pad-val]
(let [pad-row (repeat (+ 4 (count (first in-map))) pad-val)
pad-side (repeat 2 pad-val)]
(mapv vec
(concat
[pad-row pad-row]
(mapv #(concat pad-side % pad-side) in-map)
[pad-row pad-row]))))
(defn get-number [in-map y x]
(concat (subvec (get in-map (dec y)) (dec x) (+ 2 x))
(subvec (get in-map y) (dec x) (+ 2 x))
(subvec (get in-map (inc y)) (dec x) (+ 2 x))))
(defn get-new-pixel [enhance-algo in-map y x]
(->> (get-number in-map y x)
str/join
(#(Integer/parseInt % 2))
(get enhance-algo)
{\. 0 \# 1}))
(defn build-output-number-map [enhance-algo in-map]
(let [pad-val (if (= \# (first enhance-algo)) (first (first in-map)) 0)
padded-in-map (pad-input-map in-map pad-val)]
(for [y (range 1 (dec (count padded-in-map)))]
(for [x (range 1 (dec (count (first padded-in-map))))]
(get-new-pixel enhance-algo padded-in-map y x)
))))
(defn count-lit-pixels [in-map]
((frequencies (flatten in-map)) 1))
(let [[enhance-algo in-map]
(->> (slurp "./in")
str/split-lines
((juxt
first
(comp (partial mapv #(mapv {\. 0 \# 1} %))
(partial drop 2)))))
image-output (iterate (partial build-output-number-map enhance-algo) in-map)]
(println (count-lit-pixels (nth image-output 50))))
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