为什么Guava不为小的ImmutableLists使用专门的类？(Why does Guava not use specialized classes for small ImmutableLists?)

 我的意思是没有冒犯，但我花了一段时间来理解你的代码。 当您打算让其他人阅读时，您可能需要更明确地命名您的方法和参数。 
 
 作为一个局外人，我花了一段时间来理解你的代码中的s实际上代表了target_number 。 评论您的方法以指示如何使用它们以及预期的返回值应该是什么，这也是一个好主意。 
 
integers = [1,2,3,4,5,6,7,8,9,3,4,5,6,7,8,4,3,2,1]
target_number = 10
$current_index = [0]

def set_right_index(integers, leftmost_index, leftmost_int, target_number)
  integers.each_with_index do |int, i|
    next if i <= leftmost_index
    return i if int == target_number - leftmost_int
  end
  nil
end

def find_pairs(integers, target_number)
  sums = {}

  integers.each_with_index do |int, i|
    next if i < $current_index.max
    # debug = []
    # debug << set_right_index(integers, i, int, target_number)
    right_index = set_right_index(integers, i, int, target_number)

    if right_index.nil?
      return sums if i == integers.length - 1
      next
    end

    sums[right_index] = [int, (target_number - int)]
    $current_index << i
    # sums.merge! sum_pairs(integers[0..right_index], target_number)  #<= calling this returns a `stack overflow error` :P because the methods just keeps calling itself
    sums
  end
end
 
 现在，如果你打电话 
 
find_pairs(integers, target_number)
 
 返回值将如下所示： 
 
{8=>[1, 9],
 7=>[2, 8],
 6=>[3, 7],
 5=>[4, 6],
 11=>[5, 5],
 10=>[6, 4],
 9=>[7, 3],
 17=>[8, 2],
 18=>[9, 1],
 13=>[3, 7],
 12=>[4, 6],
 15=>[6, 4],
 16=>[7, 3]}
 
 你说： 
 
 
 
 问题是它返回一个散列，最左边的索引作为键，而对作为值。 我试图从另一个函数（#sum_pairs）调用这个递归函数，这样我就可以格式化我需要的输出 
 
 
 请告诉我你到底是什么意思， so that I can then format the output I need你想要最终结果怎么样？ 
 
 编辑＃1 
 
 出于调试目的，我将所有结果放在一个数组中，结果如下所示 
 
integers = [1,2,3,4,5,6,7,8,9,3,4,5,6,7,8,4,3,2,1]
target_number = 10

=> [{:left_index=>0, :right_index=>8, :values=>[1, 9]},
 {:left_index=>1, :right_index=>7, :values=>[2, 8]},
 {:left_index=>2, :right_index=>6, :values=>[3, 7]},
 {:left_index=>3, :right_index=>5, :values=>[4, 6]},
 {:left_index=>4, :right_index=>11, :values=>[5, 5]},
 {:left_index=>5, :right_index=>10, :values=>[6, 4]},
 {:left_index=>6, :right_index=>9, :values=>[7, 3]},
 {:left_index=>7, :right_index=>17, :values=>[8, 2]},
 {:left_index=>8, :right_index=>18, :values=>[9, 1]},
 {:left_index=>9, :right_index=>13, :values=>[3, 7]},
 {:left_index=>10, :right_index=>12, :values=>[4, 6]},
 {:left_index=>12, :right_index=>15, :values=>[6, 4]},
 {:left_index=>13, :right_index=>16, :values=>[7, 3]},
 {:left_index=>14, :right_index=>17, :values=>[8, 2]}]
 
 请告诉我您希望最终结果如何，以便我可以尝试一下。 

I mean no offense but it took me a while to understand your code. You may need to name your methods and parameters more explicitly when you intend other people to read. 
 
As an outsider, It took me a while to understand the s throughout your code actually represented the target_number. It's also a good idea to comment your methods indicating how to use them and what the expected return value should be.
 
integers = [1,2,3,4,5,6,7,8,9,3,4,5,6,7,8,4,3,2,1]
target_number = 10
$current_index = [0]

def set_right_index(integers, leftmost_index, leftmost_int, target_number)
  integers.each_with_index do |int, i|
    next if i <= leftmost_index
    return i if int == target_number - leftmost_int
  end
  nil
end

def find_pairs(integers, target_number)
  sums = {}

  integers.each_with_index do |int, i|
    next if i < $current_index.max
    # debug = []
    # debug << set_right_index(integers, i, int, target_number)
    right_index = set_right_index(integers, i, int, target_number)

    if right_index.nil?
      return sums if i == integers.length - 1
      next
    end

    sums[right_index] = [int, (target_number - int)]
    $current_index << i
    # sums.merge! sum_pairs(integers[0..right_index], target_number)  #<= calling this returns a `stack overflow error` :P because the methods just keeps calling itself
    sums
  end
end
 
Now, if you call
 
find_pairs(integers, target_number)
 
the return value will look like this:
 
{8=>[1, 9],
 7=>[2, 8],
 6=>[3, 7],
 5=>[4, 6],
 11=>[5, 5],
 10=>[6, 4],
 9=>[7, 3],
 17=>[8, 2],
 18=>[9, 1],
 13=>[3, 7],
 12=>[4, 6],
 15=>[6, 4],
 16=>[7, 3]}
 
and you said: 
 
 
 
problem is it returns a hash with the leftmost index as key and the pair as value. I'm trying to call this recursive function from another function (#sum_pairs) so that I can then format the output I need
 
 
Please tell me exactly what you mean by so that I can then format the output I need How would you like the final result to be like?
 
EDIT#1
 
For debugging purposes, I put all the results in an array instead and the result looks like this
 
integers = [1,2,3,4,5,6,7,8,9,3,4,5,6,7,8,4,3,2,1]
target_number = 10

=> [{:left_index=>0, :right_index=>8, :values=>[1, 9]},
 {:left_index=>1, :right_index=>7, :values=>[2, 8]},
 {:left_index=>2, :right_index=>6, :values=>[3, 7]},
 {:left_index=>3, :right_index=>5, :values=>[4, 6]},
 {:left_index=>4, :right_index=>11, :values=>[5, 5]},
 {:left_index=>5, :right_index=>10, :values=>[6, 4]},
 {:left_index=>6, :right_index=>9, :values=>[7, 3]},
 {:left_index=>7, :right_index=>17, :values=>[8, 2]},
 {:left_index=>8, :right_index=>18, :values=>[9, 1]},
 {:left_index=>9, :right_index=>13, :values=>[3, 7]},
 {:left_index=>10, :right_index=>12, :values=>[4, 6]},
 {:left_index=>12, :right_index=>15, :values=>[6, 4]},
 {:left_index=>13, :right_index=>16, :values=>[7, 3]},
 {:left_index=>14, :right_index=>17, :values=>[8, 2]}]
 
Please let me know how you want the end result to be like so I can give it a try.