Project - Binary Search Trees: Instructions revised for binary search tree implementation

[kyak15]

kyak15 changes to confusing wording/requirements for the BST assignment.

Because

The PR is to fix confusing wording/requirements in the Binary Search Tree assignment. The original issue asked the user to create a Tree class with an array, but to also use that array in the buildTree function. Thus creating confusion on an object or class directed approach for BST implementation. In my changes, I instruct the user to follow a class directed approach. The use of creating a BST with an unsorted or sorted array is not an option either. The 'Tree' class is initialized with a root of null. The user is then instructed to create the following methods inside the 'Tree' class:

• findValue
• insert
• delete
• height
• depth
• inOrder traversal
• postOrder traversal
• preOrder traversal
• levelOrder
• isBalanced
• reBalance
• buildTree

The first 9 methods allow the user to focus on core BST methods and operations, without needing to worry about inheriting an array to sort and check for duplicates. After successfully implementing the core methods, the user can then use an array of the current tree values to check for balance issues. If the BST is unbalanced, reBalance uses a traversal method to get an array of values from the tree, and buildTree is called to re-balance the tree.

This PR

• re-wrote certain portions of the instructions to direct the user to take a class approached implementation.
• re-writes included instructions to create methods within the 'tree' class.
• re-writes included linking the user to the MDN page regarding classes and methods in JavaScript
• re-ordered some of the existing instructions to allow the user to focus on core BST methods first.

Issue

Related to #27620

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[MaoShizhong]

Thanks @kyak15. This is a big PR that really should have started out as an issue, so you could discuss ideas with the team and we can collectively decide what work needs to be done, if any. This avoids you doing a bunch of work that we wouldn't accept for reasons that could have been discussed in the issue.

I will defer most of this to other maintainers who are more involved with the DSA side of the curriculum, but there are a couple of things I'd like to mention and some I'll push back on.

• We purposely use class/factory because either are fine. We do not need to enforce the use of a class here.
• If the instance accepts an array when instantiated, why set the root to null? That would make the array redundant. The point of passing in an array is that the buildTree method takes that array, builds the tree from it, then returns the root node which is set as the tree's root, which is our intention. In class terms, this would happen in the constructor.

  class Tree {
    constructor(array) {
      this.root = this.buildTree(array);
    }
    // ...

  If this step's wording has been a noticeable pain point in the community, then a more appropriate resolution would be to discuss improving its wording to be clearer on what's expected, of course without giving too much away.