gistfile1.txt

MODE_EASY      = 1
MODE_DIFFICULT = 2

OP_ADD   = 0
OP_SUB   = 1
OP_MULTI = 2
OP_DIV   = 3

QUESTIONS = 100

class Question
  attr_reader :left, :right, :operator

  def self.create(mode)
    if mode == MODE_EASY
      Question.new(1, 3)
    elsif mode == MODE_DIFFICULT
      Question.new(2, 4)
    else
      raise ArgumentError
    end
  end

  def initialize(keta, operator)
    @left     = rand(10 ** keta)
    @right    = rand(10 ** keta)
    if  (@right != 0) && (@left % @right == 0) 
      @operator = rand(operator)
    else
      @operator = rand(3)
    end
  end

  def answer
    case @operator
      when OP_ADD
        @left + @right
      when OP_SUB
        @left - @right
      when OP_MULTI
        @left * @right
      when OP_DIV 
        @left / @right
    end
  end

  def to_s
    case @operator
      when OP_ADD
        sprintf('%2d + %2d = ?', @left, @right)
      when OP_SUB
        sprintf('%2d - %2d = ?', @left, @right)
      when OP_MULTI
        sprintf('%2d * %2d = ?', @left, @right)
      when OP_DIV 
        sprintf('%2d / %2d = ?', @left, @right)
    end
  end
end

puts sprintf('計算 %d 開始', QUESTIONS)
print '難易度を選択してください。　1:かんたん 2:むずかしい > '
level = gets.chomp.to_i
questions = Array.new
if (level == MODE_EASY) || (level == MODE_DIFFICULT) 
  QUESTIONS.times do
    questions << Question.create(level)
  end
else
  raise "Invalid Level"
end

try_count     = 0
collect_count = 0
start_time = Time.now

questions.each do |e|
  try_count += 1
  print e.to_s
  print ' > '
  answer = gets.chomp.to_i
  if answer == e.answer
    puts '正解！'
    collect_count += 1
  else
    puts '不正解！'
  end
  if try_count % 10 == 0
    puts sprintf('%d 問突破', try_count)
  end
end

puts sprintf('%d 問終了しました', try_count)
finish_time = Time.now

time = finish_time - start_time

puts sprintf('正解　：%d', collect_count)
puts sprintf('不正解：%d', try_count - collect_count)
puts sprintf('タイム：%d分%d秒', time / 60, time % 60)