Re: not understanding return statement

If you want to see a working implementation of binary search trees in Ruby,
you may want to take a look at this:
https://medium.com/amiralles/mastering-data-structures-in-ruby-avl-trees-6206bf2035e0

Also, for other data structures:
https://medium.com/amiralles

Take a look at those posts first, and let me know if you need some help.

~ Ale Miralles.


On Wed, 12 Dec 2018 at 08:16, Andy Jones <[email protected]> wrote:

> In your method #insert, root is just a variable.  Putting   `root` as the
> last statement in #insert will return the value of that variable *from
> the #insert method*.
>
>
>
> But it won’t set the @root attribute on the class, which is what you are
> reading when you say `p x.root`.  @root is an attribute on the class
> BinarySearchTree; root is a variable in the insert method. They are not the
> same thing.
>
>
>
> I suspect you need to go back and learn some more about classes and
> attributes – sorry.
>
>
>
> *From:* ruby-talk [mailto:[email protected]] *On Behalf Of *Igor
> Maljkovic
> *Sent:* 12 December 2018 10:08
> *To:* [email protected]
> *Subject:* not understanding return statement
>
>
>
> Hi all, I need help understanding part of my code. I'm learning about data
> structures, at the moment binary search tree.
>
> This code does what I want, but I don't understand return statement in
> insert
>
> method. Why @root = root works as it works. If i put last line just root,
>
> global variable root is nil instead of tree filled with nodes.
>
> Here is my code:
>
> class *BinarySearchTree*
>
>
>
>   class *Node*
>
>     attr_accessor :value, :left_child, :right_child
>
>     def initialize(*value*)
>
>       @value = value
>
>       @left_child = nil
>
>       @right_child = nil
>
>     end
>
>   end
>
>
>
>   attr_accessor :root
>
>   def initialize()
>
>     @root = nil
>
>   end
>
>
>
>   def insert(*root* = @root, *value*)
>
>     if root == nil
>
>       root = *Node*.new(value)
>
>     elsif value <= root.value
>
>       root.left_child = insert(root.left_child, value)
>
>     else
>
>       root.right_child = insert(root.right_child, value)
>
>     end
>
>     @root = root #works with this return statement
>
>     #root <- doesn't work with this statement, why!!!
>
>   end
>
> end
>
>
>
> x = *BinarySearchTree*.new()
>
> x.insert(15)
>
> x.insert(10)
>
> p x.root
>
>
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