Y箱

コンセプトはすぐに思いついたんだけど、実現するのに時間がかかってしまった。
Clojureにもだいぶ慣れてきたんだけどねぇ。

あと、しばらく「5つ」だと思いこんでやってて、結果が合わなくて、なんでだー!ってしばらく騒いでしまった。 あほ。

17msec。 いいんじゃない？
でも、最後の計算のところがちょっときれいじゃないなぁ。

;; Problem 11  : 2011/4/11
;;  "Elapsed time: 16.602669 msecs"
(def target-grid 
[[ 8  2 22 97 38 15  0 40  0 75  4  5  7 78 52 12 50 77 91  8]
 [49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48  4 56 62  0]
 [81 49 31 73 55 79 14 29 93 71 40 67 53 88 30  3 49 13 36 65]
 [52 70 95 23  4 60 11 42 69 24 68 56  1 32 56 71 37  2 36 91]
 [22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80]
 [24 47 32 60 99  3 45  2 44 75 33 53 78 36 84 20 35 17 12 50]
 [32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70]
 [67 26 20 68  2 62 12 20 95 63 94 39 63  8 40 91 66 49 94 21]
 [24 55 58  5 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72]
 [21 36 23  9 75  0 76 44 20 45 35 14  0 61 33 97 34 31 33 95]
 [78 17 53 28 22 75 31 67 15 94  3 80  4 62 16 14  9 53 56 92]
 [16 39  5 42 96 35 31 47 55 58 88 24  0 17 54 24 36 29 85 57]
 [86 56  0 48 35 71 89  7  5 44 44 37 44 60 21 58 51 54 17 58]
 [19 80 81 68  5 94 47 69 28 73 92 13 86 52 17 77  4 89 55 40]
 [ 4 52  8 83 97 35 99 16  7 97 57 32 16 26 26 79 33 27 98 66]
 [88 36 68 87 57 62 20 72  3 46 33 67 46 55 12 32 63 93 53 69]
 [ 4 42 16 73 38 25 39 11 24 94 72 18  8 46 29 32 40 62 76 36]
 [20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74  4 36 16]
 [20 73 35 29 78 31 90  1 74 31 49 71 48 86 81 16 23 57  5 54]
 [ 1 70 54 71 83 51 54 69 16 92 33 48 61 43 52  1 89 19 67 48]])

;; add all 4 series
(defn product-of-4-line [target-lst]
  (loop [[n1 n2 n3 n4 :as tgt] target-lst
         res []]
    (if (< (count tgt) 4)
      res
      (recur (rest tgt) (conj res (* n1 n2 n3 n4) )))))

(defn product-of-4-grid [tgt-grid]
  (map #(product-of-4-line %) tgt-grid))

;; test data
(def target-grid 
 [[ 1  2  3  4]
  [11 12 13 14]
  [21 22 23 24]
  [31 32 33 34]])

;; transpose
;;   -->
;; ((1 11 21 31)
;;  (2 12 22 32)
;;  (3 13 23 33)
;;  (4 14 24 34))
;; function ver
(defn transpose-grid [grid]
  ^{:doc "Transpose grid. "}
  (apply map list grid))
;; macro ver
(defmacro transpose-grid [grid]
  `(map list ~@grid))


;; stagger
;;   right-->
;; ((1  2  3  4  x  x  x)
;;  (x 11 12 13 14  x  x)
;;  (x  x 21 22 23 24  x)
;;  (x  x  x 31 32 33 34))
;;   left-->
;; (( x  x  x  1  2  3  4)
;;  ( x  x 11 12 13 14  x)
;;  ( x 21 22 23 24  x  x)
;;  (31 32 33 34  x  x  x))
(defn stagger-right [grid]
  (let [add-x (fn [n m lst] (concat (repeat n 'x) lst (repeat m 'x)))]
    (for [line-num (range (count grid))]
      (add-x line-num (dec (- (count grid) line-num)) (nth grid line-num)))))

(defn stagger-left [grid]
  (let [add-x (fn [n m lst] (concat (repeat n 'x) lst (repeat m 'x)))]
    (for [line-num (range (count grid))]
      (add-x (dec (- (count grid) line-num)) line-num (nth grid line-num)))))

;; remove-x
;; ( x  x 11 12 13 14  x) -> (11 12 13 14)
(defn remove-x [coll]
  (remove #(= % 'x) coll))

(apply max
 (map #(apply max %)
      (filter #(not (= % []))
       (concat
        (product-of-4-grid target-grid)
        (product-of-4-grid (transpose-grid target-grid))
        (product-of-4-grid 
                  (map #(remove-x %) 
                       (transpose-grid (stagger-right target-grid))))
        (product-of-4-grid 
                  (map #(remove-x %) 
                       (transpose-grid (stagger-left target-grid))))))))
;;