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leetwinski/advent_2020_15.clj

Last active December 24, 2020 10:49
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advent of code 2020-15
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advent_2020_15.clj
(ns advent-2020-15)
(def seed [1,2,16,19,18,0])
(defn next-num [[data [i n]]]
[(assoc data n i)
[(inc i)
(- i (data n i))]])
(defn nth-num [seed n]
(->> [(into {} (map vector (butlast seed) (range)))
[(dec (count seed)) (last seed)]]
(iterate next-num)
(map second)
(drop-while #(< (first %) (dec n)))
first))
;; part 1
(nth-num seed 2020)
;; part 2
(nth-num seed 30000000)
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