golf

2024/src/day19.clj

@@ -2,32 +2,48 @@
   (:require [clojure.string :as str]
             input-manager))
 
+(def word-sizes (memoize (comp distinct (partial map count))))
+
+(defn increment-counts-for-matching-words [words puzzle counts pos]
+  (let [weight (if (= pos 0)
+                 1
+                 (get counts (dec pos)))]
+    (->> (map (partial + pos) (word-sizes words))
+         (filter (partial >= (count puzzle))) ;; prevent NPE on substring overflow
+         (map (partial subs puzzle pos))
+         (filter words)
+         (map (comp (partial + pos) dec count))
+         (reduce (fn [acc idx] (update acc idx (partial + weight)))
+                 counts))))
+
+(defn valid-combination-count [words puzzle]
+  (->> (range 0 (count puzzle))
+       (reduce (partial increment-counts-for-matching-words words puzzle)
+               (mapv (constantly 0) puzzle))
+       last))
+
 (let [[w _ & p]
       (input-manager/get-input 2024 19)]
   (def words (into #{} (str/split w #", ")))
-  (def puzzles p)
-  (def word-sizes (->> words (map count) distinct)))
-
-(defn valid-combination-count
-  ([puzzle]
-   (valid-combination-count puzzle 0 1 (mapv (constantly 0) puzzle)))
-  ;; dp is vec of ints which contains the count of combinations for substring from puzzle[0] and ending at puzzle[n]
-  ([puzzle pos weight dp]
-   (if (>= pos (count puzzle))
-     (last dp)
-     (let [dp' (->> (map (partial + pos) word-sizes)
-                    (filter (partial >= (count puzzle))) ;; prevent NPE on substring overflow
-                    (map (partial subs puzzle pos))
-                    (filter words)
-                    (map (comp (partial + pos) dec count))
-                    (reduce (fn [acc idx] (update acc idx (partial + weight)))
-                            dp))]
-       (recur puzzle (inc pos) (get dp' pos) dp')))))
+  (def puzzles p))
 
 ;; part 1 solution
-(->> (map valid-combination-count puzzles)
+(->> (map (partial valid-combination-count words) puzzles)
      (filter (partial < 0))
      count)
 
 ;; part 2 solution
-(->> (map valid-combination-count puzzles) (apply +))
+(apply + (map (partial valid-combination-count words) puzzles))
+
+(comment
+  (increment-counts-for-matching-words #{"a"} "atest" [0 0 0 0 0 0] 0)  ; [1 0 0 0 0 0]
+  (increment-counts-for-matching-words #{"a"} "btest" [0 0 0 0 0 0] 0)  ; [0 0 0 0 0 0]
+  (increment-counts-for-matching-words #{"te"} "atest" [1 0 0 0 0 0] 1) ; [1 0 1 0 0 0]
+
+  (increment-counts-for-matching-words #{"wo" "rd"} "word" [0 1 0 0] 2) ; [0 1 0 1]
+  (valid-combination-count #{"wo" "rd"} "word") ; 1
+  (valid-combination-count #{"word"} "word")    ; 1
+
+  (increment-counts-for-matching-words #{"wo" "or" "w" "rd" "d"} "word" [0 0 0 0] 0) ; [1 1 0 0]
+  (valid-combination-count #{"wo" "or" "w" "rd" "d"} "word") ; 2, because ("wo" "r" "d") and ("w")
+  )