BST tree traversals in ruby

bst_traversals.rb

# https://github.com/alexavlonitis
# BST Tree traversals in ruby, inorder, preorder and postorder using recursion
# Invert BST Tree in ruby using recursion

class Tree
  attr_accessor :root

  def initialize
    @root = nil
  end

  def preorder(node = root)
    return if node.nil?

    puts node.value
    preorder(node.left)
    preorder(node.right)
  end

  def inorder(node = root)
    return if node.nil?

    inorder(node.left)
    puts node.value
    inorder(node.right)
  end

  def postorder(node = root)
    return if node.nil?

    postorder(node.left)
    postorder(node.right)
    puts node.value
  end

  def invert(node = root)
    return if node.nil?

    temp = node.left
    node.left = node.right
    node.right = temp
    invert(node.left)
    invert(node.right)
    self
  end
end

class Node
  attr_accessor :value, :left, :right

  def initialize(value)
    @value = value
    @left = nil
    @right = nil
  end
end

=begin
      10
     /  \
    5   12
  /  \
 1   6

Inverted

      10
     /  \
   12    5
        / \
       1   6
=end

root = Node.new(10)
root.left = Node.new(5)
root.right = Node.new(12)

root.left.left = Node.new(1)
root.left.right = Node.new(6)

t = Tree.new
t.root = root

t.preorder
puts '###### Inverted ########'
inverted = t.invert
inverted.preorder