150419

Ruby


864197532（高速化）

150418(2)分を高速化してみた。

def takahashi_number(m)

  numbers = (0..9).to_a

  numbers.repeated_combination(m){|c_ary|

    # 後述のnが９の倍数ということはc_aryの和も９の倍数

    if c_ary.inject(:+) % 9 == 0

      min_ary = c_ary.clone

      max = min_ary.reverse.join.to_i

      # 最高位を0以外にする←カプレカ数との違い

      i = 0

      while min_ary[i] == 0

        i += 1

      end

      min_ary[0], min_ary[i] = min_ary[i], min_ary[0]

      min = min_ary.join.to_i

      n = max - min

      p [m, c_ary, n] if c_ary == n.to_s.split('').map(&:to_i).sort

    end

  }

end

(2..9).each{|m| takahashi_number(m)}

出力結果

[3, [4, 5, 9], 495]

[4, [1, 4, 6, 7], 6174]

[6, [0, 2, 5, 6, 6, 8], 660852]

[6, [1, 3, 4, 6, 6, 7], 631764]

[6, [4, 4, 5, 5, 9, 9], 549945]

[8, [0, 2, 3, 5, 6, 6, 6, 8], 66308652]

[8, [1, 3, 3, 4, 6, 6, 6, 7], 63317664]

[9, [1, 2, 3, 4, 5, 6, 7, 8, 9], 864197532]

[9, [4, 4, 4, 5, 5, 5, 9, 9, 9], 554999445]