path-finding.clj

(defn neighbors [board coord]
  (let [directions [[1 0] [-1 0] [0 1] [0 -1]]]
    (->> (map #(mapv + coord %) directions)
         (filter (fn [coord']
                   (= (get-in board coord') \.))))))

(defn bfs-path [board start end]
  (loop [frontier [[start [start]]]
         visited #{start}]
    (let [[[current current-path] & frontier] frontier
          unvisited-neighbors (->> current
                                   (neighbors board)
                                   (remove visited))]
      (cond (nil? current) []
            (= current end) current-path
            :else (recur (into (vec frontier)
                         (mapv #(vector % (conj current-path %)) unvisited-neighbors))
                   (into visited [current]))))))