78 lines
2.2 KiB
Clojure
78 lines
2.2 KiB
Clojure
(ns day09
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(:require [core :as c]
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[input-manager :refer [get-input]]))
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(def input (->> (first (get-input 9))
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(map str)
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(map parse-long)))
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(def smol-nums (->> input (take-nth 2) (into [])))
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(def smol-spaces (->> input rest (take-nth 2) (into [])))
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(def forward (map-indexed #(repeat %2 %1) smol-nums))
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;; part 1
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(->> forward reverse flatten
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(c/partition-by-counts smol-spaces)
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(interleave forward)
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flatten
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(take (reduce + smol-nums))
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(map-indexed *)
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(reduce +))
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(def indexed-space-counts
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(->> smol-spaces
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(map vector smol-nums)
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(reductions (fn [[acc last-spaces] [ns spaces]]
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[(+ acc ns last-spaces) spaces])
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[0 0])
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rest
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(into [])))
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(def indexed-num-counts
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(->> smol-nums
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rest
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(map vector smol-spaces)
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(reductions (fn [[acc last-ns] [spaces ns]]
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[(+ acc spaces last-ns) ns])
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[0 (first smol-nums)])
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(into [])))
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(defn get-partial-checksum [[val [idx cnt]]]
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(->> (range idx (+ idx cnt))
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(map #(* val %))
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(reduce +)))
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(defn compute-unmoved-checksum [moved]
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(->> indexed-num-counts
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(map-indexed vector)
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(filter (c/compose first moved not))
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(map get-partial-checksum)
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(reduce +)))
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(defn get-slot [v-cnt cnts]
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(some (fn [[slot [_ cnt]]]
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(when (and (<= v-cnt cnt)
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(> cnt 0))
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slot))
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(map-indexed vector cnts)))
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;; part 2
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(->> indexed-num-counts
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(map-indexed vector)
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reverse
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(reduce (fn [{:keys [acc moved cnts] :as state}
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[v [v-idx v-cnt]]]
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(let [slot (get-slot v-cnt cnts)
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move-to-idx (first (get cnts slot))]
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(if (or (nil? slot) (>= move-to-idx v-idx))
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state
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{:acc (+ acc (get-partial-checksum [v [move-to-idx v-cnt]]))
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:moved (conj moved v)
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:cnts (update cnts slot (fn [[i n]]
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[(+ i v-cnt) (- n v-cnt)]))})))
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{:acc 0
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:moved #{}
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:cnts indexed-space-counts})
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((juxt :acc (c/compose :moved compute-unmoved-checksum)))
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(apply +))
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