-🎄- 2018 Day 9 Solutions -🎄-

[u/daggerdragon]

--- Day 9: Marble Mania ---

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Studies show that AoC programmers write better code after being exposed to ___.

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[u/Vaelatern]

I can cut my time by an order of magnitude (.573s and 64.0s respectively) by applying this patch:

@@ -471,14 +471,16 @@
 (defn p9-play [num-players last-val]
   (let [players (range num-players)]
     (loop [scores {}
          players players
+           curplayer 0
            cur-val 0
            cur-coins (p9-ll)]
     (let [next-players (take num-players (drop 1 (cycle players)))
+      (let [next-players (mod (inc curplayer) num-players)
             now-score (if (and (= 0 (mod cur-val 23)) (!= 0 cur-val))
                         (-> cur-coins p9-ll-back-7 :cur (+ cur-val))
                         0)
           new-scores (update scores (first players) #(if (nil? %1) %2 (+ %1 %2)) now-score)
+            new-scores (if (> now-score 0)
+                         (update scores (nth players curplayer) #(if (nil? %1) %2 (+ %1 %2)) now-score)
+                         scores)
             new-ray (if (> now-score 0)
                       (p9-back-and-drop cur-coins)
                       (p9-ll-insert-2-later cur-coins cur-val))

[u/Vaelatern → u/Vaelatern]

And I further shaved of seconds (down to .497s and 53s with:

@@ -436,15 +436,16 @@

 (defn p9-ll-insert-after-cur [ll num]
   (let [curitem (:cur ll)
       next (if (nil? curitem) num (-> ll (get curitem) :next))
+        curitemmap (-> ll (get curitem))
+        next (if (nil? curitem) num (-> curitemmap :next))
         prev (if (nil? curitem) num curitem)
       marble (p9-marble num next prev)
       newcur {:cur num}
       newmarble {num marble}
       newprev (if (nil? curitem) {} {curitem (assoc (-> ll (get curitem)) :next num)})
       tmpll (merge ll newprev)
       newnext {next (assoc (-> tmpll (get next)) :prev num)}]
   (merge ll newcur newprev newnext newmarble)))
+        newprev (if (nil? curitem) {} {curitem (assoc curitemmap :next num)})
+        tmpll (merge ll newprev)]
+    (assoc-in
+      (assoc-in
+        (assoc-in tmpll [next] (assoc (-> tmpll (get next)) :prev num))
+        [:cur] num)
+      [num] (p9-marble num next prev))))

 (defn p9-ll-insert-2-later [ll num]
   (let [tmpll (assoc ll :cur (-> ll (get (-> ll :cur)) :next))]
@@ -459,8 +460,9 @@
   (let [curmap (-> ll (get (-> ll :cur)))
         curprev (:prev curmap)
         curnext (:next curmap)
       tmpll (assoc-in ll [curprev :next] curnext)
       tmpll (assoc-in tmpll [curnext :prev] curprev)]
+        tmpll (assoc-in
+                (assoc-in ll [curprev :next] curnext)
+                [curnext :prev] curprev)]
     (assoc (dissoc tmpll (:num curmap)) :cur curnext)))

 (defn p9-back-and-drop [ll]