feat(data-struct): binary search tree

[zFlxw]

This is an implementation of a binary search tree. If there are any inconveniences, please comment here, so I can improve the code.

[appgurueu]

Looks correct overall. However:

• You should not expose implementation details like the TreeNode<T>. From the outside, your BinarySearchTree<T> should behave just like a SortedSet<T> implementation.
• Your traversals should not take a TreeNode<T>; instead, they should all start at the root node. It'd be reasonable to implement them using either a closure (as you did with findMin/findMax) or methods of the TreeNode<T> helper class.

[zFlxw]

I resolved most of the things you mentioned directly in the code. However, I am a bit confused with the first point you mentioned as a comment. 😅

You should not expose implementation details like the TreeNode. From the outside, your BinarySearchTree should behave just like a SortedSet implementation.

Am I right with the assumption that this point was related to the search() function, where TreeNode<T> was returned? If so, it should be alright now. If you meant something else, please reach out to me again.

[appgurueu]

Am I right with the assumption that this point was related to the search() function, where TreeNode<T> was returned? If so, it should be alright now. If you meant something else, please reach out to me again.

It was related to the traversals as well. You have addressed it properly.

[raklaptudirm]

Tests are failing.