gistfile1.rb

def delete(value, node = @root)
  return if node.nil?

  if x < node.value
    node.left = delete(x, node.left)
  elsif x > node.value
    node.right = delete(x, node.right)
  else
    if node.left.nil?
      return node.right
    elsif node.right.nil?
      return node.left
    end

    succesor = first_in_order(node.right)
    node.value = successor.value
    node.right = delete(successor.value, node.right)
  end

  node
end

def first_in_order(node)
  return node if node.left.nil?

  first_in_order(node.left)
end