Here is the interview question prompt, presented for reference.

Write a method to determine how deep a binary tree goes. The tree's depth can be described as the number of nodes you encounter as you traverse from the root node to a leaf.

The root node is the topmost node, and a leaf is a node with no children.

For example, you're given the following binary tree:

    6
   / \
  2  14
    /  \
   13   19

The longest distance is from 6 to 19, and we return 3 because it covers 3 nodes.

The method will be invoked like the following:

const root = new Node(6);

function howDeep(root) {
    return;
};

howDeep(root);

Constraints

• Number of nodes in the tree <= 100000
• The nodes will always contain integer values between -1000000000 and 1000000000
• Expected time complexity : O(logn)
• Expected space complexity : O(n) considering the call stack

You can see the full challenge with visuals at this link.