traversal of binary tree

binary_tree_traversal.rb

class Node
  attr_accessor :data, :left, :right

  def initialize(d, l = nil, r = nil)
    self.data = d
    self.left = l
    self.right = r
  end
end

def traverse_preorder(tree)
  return if tree.nil?

  puts tree.data
  traverse_preorder(tree.left)
  traverse_preorder(tree.right)
end

def traverse_inorder(tree)
  return if tree.nil?

  traverse_inorder(tree.left)
  puts tree.data
  traverse_inorder(tree.right)
end

def traverse_postorder(tree)
  return if tree.nil?

  traverse_postorder(tree.left)
  traverse_postorder(tree.right)
  puts tree.data
end

tree = Node.new(1,
            Node.new(2,
                 Node.new(3,
                      Node.new(4),
                      Node.new(5,
                           Node.new(6),
                           Node.new(7))),
                 Node.new(8,
                      Node.new(9),
                      Node.new(10))
                 ),
            Node.new(11,
                 Node.new(12),
                 Node.new(13)))

traverse_preorder(tree)
puts
traverse_inorder(tree)
puts
traverse_postorder(tree)
# >> 1
# >> 2
# >> 3
# >> 4
# >> 5
# >> 6
# >> 7
# >> 8
# >> 9
# >> 10
# >> 11
# >> 12
# >> 13
# >>
# >> 4
# >> 3
# >> 6
# >> 5
# >> 7
# >> 2
# >> 9
# >> 8
# >> 10
# >> 1
# >> 12
# >> 11
# >> 13
# >>
# >> 4
# >> 6
# >> 7
# >> 5
# >> 3
# >> 9
# >> 10
# >> 8
# >> 2
# >> 12
# >> 13
# >> 11
# >> 1