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(defn get-adj [in y x]
(filter
#(some? (get-in in %))
[[(dec y) (dec x)] [(dec y) x] [(dec y) (inc x)]
[y (dec x)] [y (inc x)]
[(inc y) (dec x)] [(inc y) x] [(inc y) (inc x)]]
))
(defn apply-incs [in] (mapv (partial mapv inc) in))
(defn next-step [indata]
(loop [in (apply-incs (indata :grid)) bl (indata :blinks) y 0 x 0]
(cond
(> (get-in in [y x]) 9)
(do
(recur
(-> (reduce
(fn [i n] (update-in i n #(cond-> % (pos? %) inc)))
in
(get-adj in y x))
(update-in [y x] #(do % 0)))
(inc bl)
0 0))
(< x (dec (count (first in))))
(recur in bl y (inc x))
(< y (dec (count in)))
(recur in bl (inc y) 0)
:else
{:grid in :blinks bl}
)
)
)
(->> (slurp "./in")
(clojure.string/split-lines)
(map (partial map #(- (int %) 48)))
(assoc {} :blinks 0 :grid)
(iterate next-step)
(take-while #(pos? (apply + (flatten (% :grid)))))
(count)
(println))
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