Euler : Problem 11

Posted by TAKAIY On 2011年4月11日月曜日 0 コメント
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))))))))
;;


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