ruby 鲁比·科恩斯：About_Scoring_Project(准确地说，是带有.map方法的迭代器)

wwwo4jvm 于 2023-10-17 发布在 Ruby

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我是新来的我在做Ruby Koans的时候遇到了一些问题，About_Scoring_Project。.map方法根据短语的顺序返回值，而不是变量的名称。我很困惑。

def score(dice)
  total_score = 0
  side = 6
  count = Array.new
  side.times{count << 0} # [0, 0, 0, 0, 0, 0]
  # Tell the occured time of each side
  while i = dice.pop
    count[i-1] += 1
  end
  # Calculating total score
  i = 0
  count.map! do |item|
    i += 1
    if item >= 3 && i != 1
      total_score = i*100
      item - 3
    elsif item >= 3
      total_score = 1000
      item - 3
    else
      item
    end
  end
  # Count the rest
  total_score += ( count[0]*100 + count[4]*50 )
  total_score # return the total score
end

虽然这一个作品，但当我最初写道：

elsif item >= 3
  item - 3
  total_score = 1000

执行时数组计数结果为[1000，0，0，0，0]

score([1,1,1]) # score([1,1,1]) = 101000 which should be 1000

也就是说，它将值1000赋予item而不是total_value。但是当我像上面指出的那样改变两个短语的顺序时，它就能正确工作。有人能帮我一下吗。我是Ruby和编程的新手。原谅我蹩脚的英语…
项目背景：

# Greed is a dice game where you roll up to five dice to accumulate
# points.  The following "score" function will be used to 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.

ruby

来源：https://stackoverflow.com/questions/41956107/ruby-koans-about-scoring-project-precisely-iterator-with-map-method

3条答案

按热度按时间

irtuqstp1#

.map方法根据短语的顺序返回值，而不是变量的名称。我很困惑。
或多或少是的。块只是返回最后一个表达式的值，很像方法。
如果您有：

count.map! do |item|
  item - 3
  total_score = 1000
end

那么total_score = 1000，它的计算结果是1000，是块的返回值。
如果您有：

count.map! do |item|
  total_score = 1000
  item - 3
end

那么item - 3是块的返回值。
map!又创建了一个新数组，其中包含块中的值。

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赞(0）回复(0）举报 2023-10-17

bmp9r5qi2#

还有一种方法：

def three_of_a_kind(dice, count)
  count * (dice == 1 ? 1000 : 100 * dice)
end
def no_set(dice, count)
  case dice
  when 1
    count * 100
  when 5
    count * 50
  else
    0
  end
end
def score(rolls)
  rolls.group_by(&:itself).map do |dice, throws|
    n = throws.size
    three_of_a_kind(dice, n / 3) + no_set(dice, n % 3)
  end.inject(:+)
end
p score([1, 1, 1, 5, 1]) == 1150
p score([2, 3, 4, 6, 2]) == 0
p score([3, 4, 5, 3, 3]) == 350
p score([1, 5, 1, 2, 4]) == 250

顺便说一下：

side = 6
  count = Array.new
  side.times{count << 0}

就是：

Array.new(6){ 0 }

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赞(0）回复(0）举报 2023-10-17

lmvvr0a83#

def score(dice)
  sum = 0
  dice.tally.each do |x, n|
    sum += n / 3 * (x == 1 ? 1000 : x * 100) + n % 3 * (x == 1 ? 100 : x == 5 ? 50 : 0)
  end
  sum
end

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ruby 鲁比·科恩斯：About_Scoring_Project(准确地说，是带有.map方法的迭代器)

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