Y箱

パターンがあるので、それを数えるのがいいかなと思ったんだけど、それだと、手で計算できちゃうので、なんならということで、1000までの数字を読み下ろす関数を作ってみた。

user> (writedown 999)
"nine hundred and ninety nine"

ということで、あえて力ずく。

関係ないけど、four で fourteen なのに forty なんだね。「u」はどこへいっちゃうんだろ。
この問題を解くまで気づかなかったというか、忘れていたというか、ねぇ。

;;
;; Problem 17  : 2011/4/22
;; "Elapsed time: 106.548179 msecs"
(def number-table
  '{ 1        "one"
     2        "two"
     3        "three"
     4        "four"
     5        "five"
     6        "six"
     7        "seven"
     8        "eight"
     9        "nine"
     10        "ten"
     11        "eleven"
     12        "twelve"
     13        "thirteen"
     14        "fourteen"
     15        "fifteen"
     16        "sixteen"
     17        "seventeen"
     18        "eihgteen"
     19        "nineteen"
    20         "twenty"
    30         "thirty"
    40         "forty"
    50         "fifty"
    60         "sixty"
    70         "seventy"
    80         "eighty"
    90         "ninety"
    100        "hundred" })

(defn writedown-tys [n]
  (cond (<= n 0) nil
        (< n 20)
          (number-table n)
        :else
          (apply str (interpose " "
                    (list (number-table (* 10 (floor (/ n 10))))
                          (number-table (rem n 10)))))))

(defn writedown-hdrs [n]
  (cond (<= n 0) nil
        :else (apply str (interpose " "
                      (list (number-table n)
                            "hundred")))))
        
(defn writedown [n]
  (if (= n 1000)
    "one thousand"
  (let [hundreds (floor (/ n 100))
        tys (rem n 100)]
    (apply str
           (interpose " "
                      (filter #(not (nil? %))
                              (list
                               (writedown-hdrs hundreds)
                               (if (and (> hundreds 0) (> tys 0))
                                 "and"
                                 nil)
                               (writedown-tys tys))))))))

        
(loop [nums (range 1 1001) total 0]
  (if (empty? nums)
    total
    (recur (rest nums)
           (+ total
              (.length (.replace (writedown (first nums)) " " ""))))))

;;