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it was math all along....

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This commit is contained in:
Adam Jeniski 2025-08-29 11:38:14 -09:00
parent f60fc29a23
commit 125891900b
1 changed files with 31 additions and 45 deletions
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76
2024/src/day13.clj
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@ -4,58 +4,44 @@
[input-manager :refer [get-input-raw]])) [input-manager :refer [get-input-raw]]))
(def input (def input
(->> (get-input-raw 13) (->> (get-input-raw 2024 13)
c/split-on-double-newlines c/split-on-double-newlines
(map #(c/get-match-groups #"(\d+)" %)) (map #(c/get-match-groups #"(\d+)" %))
(c/mmap first) (c/mmap first)
(c/mmap parse-long) (c/mmap parse-long)
(map #(map vector [:ax :ay :bx :by :px :py] %)) (map #(map vector [:ax :ay :bx :by :px :py] %))
(map #(into {} %)) (map #(into {} %))))
;
))
(defn push [m k vs]
(if (empty? vs)
m
(update m k #(if (nil? %1)
(set vs)
(into %1 %2))
vs)))
(defn get-cost [{:keys [ax ay bx by px py]}] (defn get-cost [{:keys [ax ay bx by px py]}]
(loop [costs (sorted-map 0 #{[0 0]}) ;; systems of equations. had to get out a pen and paper to work out a and b ;P
i 0] ;; px = ax * a + bx * b
(let [[cost locs] (first costs) ;; py = ay * a + by * b
costs' (dissoc costs cost)] (let [b (/ (- (* ax py)
(if (or (nil? cost) (* ay px))
(> i 1000) (- (* ax by)
(some (fn [[x y]] (* bx ay)))
(and (= x px) a (/ (- px (* b bx))
(= y py))) ax)]
locs)) (when (= 0.0
costs (mod a 1.0)
(recur (-> costs' (mod b 1.0))
(push (+ cost 3) (+ (* 3 a) b))))
(->> locs
(map #(-> %
(update 0 + ax)
(update 1 + ay)))
(filter (fn [[x y]]
(and (<= x px)
(<= y py))))))
(push (+ cost 1)
(->> locs
(map #(-> %
(update 0 + bx)
(update 1 + by)))
(filter (fn [[x y]]
(and (<= x px)
(<= y py)))))))
(inc i))))))
(comment
;; part 1 ;; part 1
(->> input (->> input
(map get-cost) (map get-cost)
(filter identity) (filter identity)
(reduce +)) (filter identity)
(reduce +)
;
)
(def offset 10000000000000)
(->> input
(map #(update % :px + offset))
(map #(update % :py + offset))
(map get-cost)
(filter identity)
(reduce +)))