dc201208078

gistfile1.cs

using System;
using System.Collections;
using System.Linq;

namespace Application
{
    class MainClass
    {
        /*
         * 1 から 5 までの数字を英単語で書けば one, two, three, four, five であり、全部で 3 + 3 + 5 + 4 + 4 = 19 の文字が使われている。
         * では 1 から 1000 (one thousand) までの数字をすべて英単語で書けば、全部で何文字になるか。
         * 注: 空白文字やハイフンを数えないこと。例えば、342 (three hundred and forty-two) は 23 文字、115 (one hundred and fifteen) は20文字と数える。なお、"and" を使用するのは英国の慣習。
         */

        public static void Main(string[] args)
        {
            Console.WriteLine(Enumerable.Range(1, 1000).Aggregate(0, (ag, val) => AlphaNum(val) + ag));
        }

        private static int AlphaNum(int num)
        {
            if (num >= 1 && num < 20) {
                return ONE_TO_NINETEEN[num];
            } else if (num >= 20 && num < 100) {
                return TWENTY_TO_NINETY[num / 10] + ((num % 10 == 0) ? 0 : AlphaNum(num % 10));
            } else if (num >= 100 && num < 1000) {
                return ONE_TO_NINETEEN[num / 100] + HUNDRED + ((num % 100 == 0) ? 0 : (AND + AlphaNum(num % 100)));
            } else if (num == 1000) {
                return ONE_TO_NINETEEN[1] + THOUSAND;
            } else { throw new NotSupportedException(); }
        }

        private static readonly int[] ONE_TO_NINETEEN = { -1, // dummy
         "ONE".Length, "TWO".Length, "THREE".Length, "FOUR".Length,
         "FIVE".Length, "SIX".Length, "SEVEN".Length, "EIGHT".Length,
         "NINE".Length, "TEN".Length, "ELEVEN".Length, "TWELVE".Length,
         "THIRTEEN".Length, "FOURTEEN".Length, "FIFTEEN".Length, "SIXTEEN".Length,
         "SEVENTEEN".Length, "EIGHTEEN".Length, "NINETEEN".Length
        };

        private static readonly int[] TWENTY_TO_NINETY = { -1, -1, // dummy
         "TWENTY".Length, "THIRTY".Length, "FORTY".Length,
         "FIFTY".Length, "SIXTY".Length, "SEVENTY".Length,
         "EIGHTY".Length, "NINETY".Length
        };

        private static readonly int HUNDRED = "HUNDRED".Length;
        private static readonly int THOUSAND = "THOUSAND".Length;
        private static readonly int AND = "AND".Length;
    }
}

// 21124