Directory of files by level

nodes_by_depth.rb

# The goal is to traverse a tree and return an array A[0...h], where h is the height
# of the tree and A[i] is an array of items at height i.
# example:
# tree -> 
#                 0
#          1              2
#       3    4        5       6
#     7  8  9 10    11 12   13 14
#
# should give you:
# [[0], [1, 2], [3, 4, 5, 6], [7, 8, 9, 10, 11, 12, 13, 14]]


class MyTree
  attr_accessor :children, :value

  def initialize(t)
    @value = t.keys.first
    @children = t[@value].map{ |child| MyTree.new(child) }
  end

  def by_depth
    queue = []
    result = []
    height = 0

    queue << self
    current_children = 1
    next_children = 0

    while( e = queue.slice!(0) )
      current_children -= 1
      if(result[height].is_a?(Array))
        result[height] << e.value
      else
        result[height] = [e.value]
      end

      if(!e.children.empty?)
        queue = queue + e.children
        next_children += e.children.count
      end

      if(current_children == 0)
        height += 1
        current_children = next_children
        next_children = 0	
      end
    end
    result
  end
end

example = {0 => [{1 => 
                    [ {3 => [
                            {7 => []}, {8 => []}
                            ]}, 
                      {4 => [
                            {9 => []}, {10 => []}
                            ]} 
                ]},
                {2 => 
                  [ {5 => [
                          {11 => []}, {12 => []}
                          ]}, 
                    {6 => [
                          {13 => []}, {14 => []}
                          ]} 
                  ]
                }]
          }

tree = MyTree.new(example)
puts tree.by_depth.inspect