Ruby Greed Koan - 如何改进我的 if/then 汤？

Question

我正在努力学习 Ruby Koans 以尝试学习 Ruby，到目前为止一切顺利。我已经得到了贪婪的公案，在撰写本文时它是 183。我有一个可行的解决方案，但我觉得我只是拼凑了一堆 if/then 逻辑，但我不是拥抱 Ruby 模式。

在下面的代码中，有什么方法可以让我更全面地接受 Ruby 模式吗？ (我的代码包含在“我的代码 [BEGINS|ENDS] HERE”注释中。

# Greed is a dice game where you roll up to five dice to accumulate
# points.  The following "score" function will be used calculate the
# score of a single roll of the dice.
#
# A greed roll is scored as follows:
#
# * A set of three ones is 1000 points
#
# * A set of three numbers (other than ones) is worth 100 times the
#   number. (e.g. three fives is 500 points).
#
# * A one (that is not part of a set of three) is worth 100 points.
#
# * A five (that is not part of a set of three) is worth 50 points.
#
# * Everything else is worth 0 points.
#
#
# Examples:
#
# score([1,1,1,5,1]) => 1150 points
# score([2,3,4,6,2]) => 0 points
# score([3,4,5,3,3]) => 350 points
# score([1,5,1,2,4]) => 250 points
#
# More scoring examples are given in the tests below:
#
# Your goal is to write the score method.

# MY CODE BEGINS HERE

def score(dice)

  # set up basic vars to handle total points and count of each number
  total = 0
  count = [0, 0, 0, 0, 0, 0]

  # for each die, make sure we've counted how many occurrencess there are
  dice.each do |die|
    count[ die - 1 ] += 1
  end

  # iterate over each, and handle points for singles and triples
  count.each_with_index do |count, index|
    if count == 3
      total = doTriples( index + 1, total )
    elsif count < 3
      total = doSingles( index + 1, count, total )
    elsif count > 3
      total = doTriples( index + 1, total )
      total = doSingles( index + 1, count % 3, total )
    end
  end

  # return the new point total
  total

end

def doTriples( number, total )
  if number == 1
    total += 1000
  else
    total += ( number ) * 100
  end
  total
end

def doSingles( number, count, total )
  if number == 1
    total += ( 100 * count )
  elsif number == 5
    total += ( 50 * count )
  end
  total
end

# MY CODE ENDS HERE

class AboutScoringProject < EdgeCase::Koan
  def test_score_of_an_empty_list_is_zero
    assert_equal 0, score([])
  end

  def test_score_of_a_single_roll_of_5_is_50
    assert_equal 50, score([5])
  end

  def test_score_of_a_single_roll_of_1_is_100
    assert_equal 100, score([1])
  end

  def test_score_of_multiple_1s_and_5s_is_the_sum_of_individual_scores
    assert_equal 300, score([1,5,5,1])
  end

  def test_score_of_single_2s_3s_4s_and_6s_are_zero
    assert_equal 0, score([2,3,4,6])
  end

  def test_score_of_a_triple_1_is_1000
    assert_equal 1000, score([1,1,1])
  end

  def test_score_of_other_triples_is_100x
    assert_equal 200, score([2,2,2])
    assert_equal 300, score([3,3,3])
    assert_equal 400, score([4,4,4])
    assert_equal 500, score([5,5,5])
    assert_equal 600, score([6,6,6])
  end

  def test_score_of_mixed_is_sum
    assert_equal 250, score([2,5,2,2,3])
    assert_equal 550, score([5,5,5,5])
  end

end

非常感谢您在我努力了解 Ruby 时提供的任何帮助。

Answer 1

哇!这里有很多非常酷的方法。我喜欢每个人的创造力。但是，我对这里提供的所有答案都有一个教学问题。 (“教育学是对……教学过程的研究。”——维基百科)

从前几个 koans(回到 about_asserts.rb)可以明显看出，启蒙之路不需要任何 Ruby 的先前/外部知识。 Path 甚至不需要先前的编程经验，这一点似乎也很清楚。因此，从教育的角度来看，这个公案必须仅使用早期公案中教授的方法、语言结构和编程技术就可以回答。这意味着:

• 没有 Enumerable#each_with_index
• 没有 Enumerable#count
• 没有 Enumerable#sort
• 没有 Hash.new(0) 指定默认值
• 没有 Numeric#abs
• 没有 Numeric#divmod
• 没有递归
• 没有案例 当
• 等等

现在，我并不是说您不允许在您的实现中使用这些东西，但公案不能要求使用它们。 必须有一个解决方案，该解决方案仅使用先前 koans 引入的构造。

此外，由于模板只是

def score(dice)
  # You need to write this method
end

这似乎暗示解决方案不应定义其他方法或类。也就是说，您应该只替换 # You need to write this method 行。

这是一个符合我的哲学要求的解决方案:

def score (dice)
    sum = 0
    (1..6).each do |i|
        idice = dice.select { |d| d == i }
        count = idice.size

        if count >= 3
            sum += (i==1 ? 1000 : i*100)
        end
        sum += (count % 3) * 100   if i == 1
        sum += (count % 3) *  50   if i == 5
    end
    sum
end

此处的方法/构造在以下 koan 文件中介绍:

Enumerable#each    about_iteration.rb
Enumerable#select  about_iteration.rb
Array#size         about_arrays.rb
a ? b : c          about_control_statements.rb
%                  about_control_statements.rb

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相关 StackOverflow 问题:

• Ruby Koans 182. Refactor help
• https://codereview.stackexchange.com/questions/423/is-this-good-ruby-ruby-koans-greed-task