AlexeiDarmin

/*
  List of depths: Given a binary tree, design an algorithm which creates a linked list of all the nodes
  at each depth (eg if you have a tree with depth D, you'll have D linked lists.)

*/

interface DepthQueue<T> {
  depth: number,
  node: T
}

AlexeiDarmin

/*
Check balanced: Implement a function to check if a binary tree is balanced. For the purposes of 
this question, a balanced tree is defined to be a tree such that the heights of the two subtrees of any
node never differ by more than one.
*/

// const myTree = buildTree([1,2,3,4,5,6,7,8, 9, 10, 11, 12, 13, 14])
const myTree = new BinaryNode(1)
myTree.rightChild = new BinaryNode(2)
myTree.rightChild.rightChild = new BinaryNode(3)

AlexeiDarmin

// Valiate binary tree: Implement a function to validate that a binary tree is a binary search tree.

function validateBST<T>(node: BinaryNode<T>) {
  if (!node) return true
  if (node.leftChild && node.leftChild.data > node.data) return false
  if (node.rightChild && node.rightChild.data < node.data) return false
  return validateBST(node.leftChild) && validateBST(node.rightChild)
}

AlexeiDarmin

/*
Developer notes:
Written in Typescript.

I chose to use an iterative approach because it's able to handle more data than a recursive approach
before hitting a stackoverfow error.

This algorithm runs in O(N) time and O(N) space, while avoiding cycles without actively searching for them. 
Actively checking for cycles would make the time compexity O(NlogN).