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53 lines
1.4 KiB
Clojure
53 lines
1.4 KiB
Clojure
(require '[clojure.string :as str])
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(def input (->> (slurp "./in2")
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str/split-lines
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((juxt
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first
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(fn [lines]
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(->> lines
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(drop 2)
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(map #(str/split % #" -> "))
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(flatten)
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(apply (partial assoc {}))
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))))))
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(def blank-map
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(reduce
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#(assoc %1 %2 0)
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{}
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(keys (second input))))
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(defn grow-polymer [polymer insertion-rules]
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(reduce
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(fn [res pair]
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(let [pk (key pair)
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p1 (str/join [(first pk) (insertion-rules pk)])
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p2 (str/join [(insertion-rules pk) (second pk)])]
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(-> res (update p1 + (val pair)) (update p2 + (val pair)))
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))
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blank-map
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(filter #(pos? (val %)) polymer)
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))
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(def growth-seq
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(iterate
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#(grow-polymer % (second input))
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(reduce
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#(update %1 %2 inc)
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blank-map
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(for [i (range 0 (dec (count (first input))))]
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(subs (first input) i (+ i 2))))))
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(let [results
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(map #(Math/ceil (/ % 2))
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(vals
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(reduce
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(fn [r p] (-> r
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(update (first (key p)) #(if (nil? %) (val p) (+ % (val p))))
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(update (second (key p)) #(if (nil? %) (val p) (+ % (val p))))))
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{}
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(nth growth-seq 40))))]
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(println (- (apply max results) (apply min results))))
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