1var assert = require('assert');
2
3function howDeep(root) {
4  if (root === null) {
5    return 0;
6  }
7
8  return Math.max(howDeep(root.left), howDeep(root.right)) + 1;
9}
10
11function Node(val) {
12  this.val = val;
13  this.left = null;
14  this.right = null;
15}
16
17// Regular binary trees
18var tree1 = new Node(4);
19tree1.left = new Node(1);
20tree1.right = new Node(3);
21
22var tree2 = new Node(5);
23tree2.left = new Node(10);
24tree2.left.left = new Node(17);
25tree2.left.right = new Node(3);
26tree2.right = new Node(8);
27
28// Binary search trees
29var tree3 = new Node(6);
30tree3.left = new Node(3);
31
32var tree4 = new Node(5);
33tree4.left = new Node(3);
34tree4.left.left = new Node(2);
35tree4.left.left.left = new Node(1);
36
37var tree5 = new Node(8);
38tree5.left = new Node(6);
39tree5.right = new Node(9);
40tree5.left.left = new Node(5);
41tree5.left.right = new Node(7);
42tree5.right.right = new Node(10);
43
44try {
45  assertIsFunction(howDeep, '`howDeep` should be a function');
46
47  console.log('PASSED: ' + '`howDeep` should be a function');
48} catch (err) {
49  console.log(err);
50}
51
52try {
53  assert.deepEqual(howDeep(tree1), 2);
54
55  console.log('PASSED: ' + 'assert.deepEqual(howDeep(tree1), 2);');
56} catch (err) {
57  console.log(err);
58}
59
60try {
61  assert.deepEqual(howDeep(tree4), 4);
62
63  console.log('PASSED: ' + 'assert.deepEqual(howDeep(tree4), 4);');
64} catch (err) {
65  console.log(err);
66}
67
68function assertIsFunction(f) {
69  return typeof f === 'function';
70}