do day16 part 1

2024/src/day16.clj

@@ -0,0 +1,98 @@
+(ns day16
+  (:require
+   [input-manager :refer [get-input]]
+   [core :as c]
+   [clojure.data.priority-map :refer [priority-map]]))
+
+(def maze
+  #_(c/split-whitespace "###############
+#.......#....E#
+#.#.###.#.###.#
+#.....#.#...#.#
+#.###.#####.#.#
+#.#.#.......#.#
+#.#.#####.###.#
+#...........#.#
+###.#.#####.#.#
+#...#.....#.#.#
+#.#.#.###.#.#.#
+#.....#...#.#.#
+#.###.#.#.#.#.#
+#S..#.....#...#
+###############")
+  (get-input 2024 16))
+(def grid (->> maze
+               (map-indexed (fn [row-idx row]
+                              (map-indexed (fn [col-idx c]
+                                             [[row-idx col-idx] c])
+                                           row)))
+               (mapcat identity)
+               (into {})))
+(defn find-char [c]
+  (->> grid
+       (filter (comp #{c} second))
+       ffirst))
+(def start (find-char \S))
+(def end (find-char \E))
+
+(defn rotate-clockwise [dir]
+  (condp = dir
+    :right :down
+    :down :left
+    :left :up
+    :up :right))
+(defn rotate-counterclockwise [dir]
+  (condp = dir
+    :down :right
+    :left :down
+    :up :left
+    :right :up))
+(defn direction-offset [dir]
+  (condp = dir
+    :up [-1 0]
+    :right [0 1]
+    :down [1 0]
+    :left [0 -1]))
+
+(defn find-search-path [[start start-dir] goal]
+  (loop [[[[pos dir] cost] & _ :as whole] (priority-map [start start-dir] 0)
+         visited #{[start start-dir]}
+         shortest {start 0}
+         n 0]
+    (if (= pos goal)
+      shortest
+      (let [searches (->> [[[(mapv + pos (direction-offset dir)) dir] (inc cost)]
+                           [[pos (rotate-clockwise dir)] (+ 1000 cost)]
+                           [[pos (rotate-counterclockwise dir)] (+ 1000 cost)]]
+                          (filter (comp not visited first))
+                          (filter (comp grid ffirst))
+                          (filter (comp not #{\#} grid ffirst)))
+            searches-no-costs (mapv (comp first pop) searches)
+            seaches-no-dirs (mapv (juxt ffirst last) searches)]
+        (recur (into (pop whole) searches)
+               (into visited searches-no-costs)
+               (into (into {} seaches-no-dirs) shortest)
+               (inc n))))))
+
+(def searched (find-search-path [start :right] end))
+
+;; part 1 solution
+(searched end)
+
+(def max-idx (->> (keys grid)
+                  (map first)
+                  (apply max)))
+(def updated-grid (->> grid
+                       (map (fn [[k :as entry]] (if (and (contains? searched k) (#{\S \E \.} (grid k)))
+                                                  [k \O]
+                                                  entry)))
+                       (into {})))
+(->> (range 0 max-idx)
+     (map (fn [row] (map #(vector row %) (range 0 max-idx))))
+     (map (partial map updated-grid))
+     (map (partial apply str))
+     (interpose "\n")
+     (apply str)
+     print)
+
+