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(ns org.vuxu.aoc2021.day15
(:require [clojure.string :as str]))
(defn parse-digit [char]
(Character/digit char 10))
(def data
(->> (slurp "day15")
(str/split-lines)
(mapv (partial mapv parse-digit))))
(defn put-in! [array [x y] v]
(assoc! (get array x) y v))
(defn find-path [m]
(let [d (mapv transient (map (partial mapv (constantly 0)) m))
l (count m)]
(put-in! d [0 0] (get-in m [0 0]))
(loop [q (conj clojure.lang.PersistentQueue/EMPTY [0 1] [1 0])]
(if (empty? q)
(- (get-in d [(dec l) (dec l)])
(get-in d [0 0]))
(let [[x y] (peek q)
upper (if (and (> x 0) (not= 0 (get-in d [(dec x) y])))
(get-in d [(dec x) y])
##Inf)
bottom (if (and (< x (dec l)) (not= 0 (get-in d [(inc x) y])))
(get-in d [(inc x) y])
##Inf)
left (if (and (> y 0) (not= 0 (get-in d [x (dec y)])))
(get-in d [x (dec y)])
##Inf)
right (if (and (< y (dec l)) (not= 0 (get-in d [x (inc y)])))
(get-in d [x (inc y)])
##Inf)
minpath (+ (get-in m [x y]) (min upper bottom left right))
]
(if (or (zero? (get-in d [x y]))
(> (get-in d [x y]) minpath))
(do
(put-in! d [x y] minpath)
(recur (cond-> (pop q)
(> x 0) (conj [(dec x) y])
(< x (dec l)) (conj [(inc x) y])
(> y 0) (conj [x (dec y)])
(< y (dec l)) (conj [x (inc y)]))))
(recur (pop q))))))))
(def part1
(find-path data))
(def data2
(let [rows (count data)
cols (count (first data))]
(vec
(for [i (range (* 5 (count data)))]
(vec (for [j (range (* 5 (count (first data))))]
(let [qi (quot i rows)
qj (quot j cols)]
(-> (get-in data [(rem i rows) (rem j cols)])
dec (+ qi qj) (mod 9) inc))))
))))
(def part2
(find-path data2)
;; => 2966
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