Day 16

Clojure/day14.clj

@@ -0,0 +1,27 @@
+(ns day14
+  (:require [clj-commons.digest :refer [md5]]))
+
+(defn hashes [it n] (pmap #(nth (iterate md5 (str it %)) n) (range)))
+
+(defn same-chars [n h]
+  (reduce (fn [a e] (if (apply = e) (reduced (first e)) a)) nil (partition n 1 h)))
+
+(defn key64 [it n]
+  (loop [i 0, [h & hr] (hashes it n) , hm {}, hs []]
+    (cond
+      (> (count hs) 63) (nth (sort hs) 63)
+      :else (let [k3 (same-chars 3 h), k5 (when k3 (same-chars 5 h))
+                  idx (when-let [c (hm k5)] (filter #(<= i (+ 1000 %)) c))]
+        ;; (when (= (mod i 1000) 0) (prn (/ i 1000) (count hs)))
+        (recur (inc i) hr (cond-> hm k3 (update k3 conj i)) (if (seq idx) (into hs idx) hs))))))
+
+;; part 1 takes around half a sec, but part 2 runs for more than a minute -- weak performance of `md5`
+
+(defn -main [day]
+  (let [it "ihaygndm", solve (partial key64 it)]
+    {:part1 (solve 1) :part2 (solve 2017)}))
+
+
+(comment
+  (= 22728 (key64 "abc" 1))             ; not testing part2, takes too long
+  )

bb.edn

@@ -1,5 +1,6 @@
 {:paths ["input" "Clojure"]
- :deps {org.clojure/math.combinatorics {:mvn/version "0.1.6"}}
+ :deps {org.clojure/math.combinatorics {:mvn/version "0.1.6"}
+        org.clj-commons/digest {:mvn/version "1.4.100"}}
  :tasks
  {:requires ([babashka.curl :as curl]
              [babashka.fs :as fs]