ariarule-4clojure-solution119.clj

;; ariarule's solution to Win at Tic-Tac-Toe
;; https://4clojure.com/problem/119

(fn [player board]
  (let [vboard (apply concat board)
        s (range 0 3)
        positions (mapcat #(map (fn [x] [% x]) s) s)
        rows (partition 3 positions)
        columns [(map first rows) (map second rows) (map #(nth % 2) rows)]
        wins (map set (concat rows columns ['([0 0] [1 1] [2 2]) '([0 2] [1 1] [2 0])]))
        piece-positions (zipmap positions vboard)
        [player-positions empty-positions] (map set (map (fn [x] (map first (filter #(= (val %) x) piece-positions))) [player :e]))
        ]
   (set 
    (filter #(-> % nil? not) (map #(if (some
                (fn [w] 
                  (clojure.set/subset? w (conj player-positions %)))
                wins)
            %)
         empty-positions)))))