pe-11.clj

;;; :s/0\ze\d/ /g
(def original-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]
   ])

(def transpose (partial apply map list))

(def mirror (partial map reverse))

; (def diagonal (partial map-indexed drop)) ;; this implementation is transpose-unsafe!
(def diagonal (partial map-indexed
                       #(concat (drop % %2)
                                (repeat % 0)
                                )))

(defn gen-grids [grid]
  [grid                                           ; W<->E
   (transpose grid)                               ; N<->S
   (transpose (diagonal grid))                    ; NE<->SW (1)
   (transpose (diagonal (reverse grid)))          ; SE<->NW (1)
   (transpose (diagonal (reverse (mirror grid)))) ; NE<->SW (2)
   (transpose (diagonal (mirror grid)))           ; SE<->NW (2)
   ])

(defn gen-prods-in-row [n row]
  (map (partial apply *) (partition n row)))

(defn solve [n]
  (apply max
         (for [grid (gen-grids original-grid)
               row grid
               p (gen-prods-in-row n row)
               ]
           p)))

• parse放棄してごめんなさい
• 実装はシンプルにしたつもりですが、「diagonal関数は何?」と聞かれたときに一言で言えないのがちょっと残念な感じです。