1var assert = require('assert');
2
3function lowestCommonAncestor(root, node1, node2) {
4  if (root.val > node1 && root.val > node2) {
5    return lowestCommonAncestor(root.left, node1, node2);
6  } else if (root.val < node1 && root.val < node2) {
7    return lowestCommonAncestor(root.right, node1, node2);
8  } else {
9    return root.val;
10  }
11}
12
13function Node(val) {
14  this.val = val;
15  this.left = null;
16  this.right = null;
17}
18
19// Regular binary trees
20var tree1 = new Node(4);
21tree1.left = new Node(1);
22tree1.right = new Node(3);
23
24var tree2 = new Node(5);
25tree2.left = new Node(10);
26tree2.left.left = new Node(17);
27tree2.left.right = new Node(3);
28tree2.right = new Node(8);
29
30// Binary search trees
31var tree3 = new Node(6);
32tree3.left = new Node(3);
33
34var tree4 = new Node(5);
35tree4.left = new Node(3);
36tree4.left.left = new Node(2);
37tree4.left.left.left = new Node(1);
38
39var tree5 = new Node(8);
40tree5.left = new Node(6);
41tree5.right = new Node(9);
42tree5.left.left = new Node(5);
43tree5.left.right = new Node(7);
44tree5.right.right = new Node(10);
45
46try {
47  assertIsFunction(
48    lowestCommonAncestor,
49    '`lowestCommonAncestor` should be a function'
50  );
51
52  console.log('PASSED: ' + '`lowestCommonAncestor` should be a function');
53} catch (err) {
54  console.log(err);
55}
56
57try {
58  assert.equal(lowestCommonAncestor(tree4, 1, 3), 3);
59
60  console.log(
61    'PASSED: ' + 'assert.equal(lowestCommonAncestor(tree4, 1, 3), 3)'
62  );
63} catch (err) {
64  console.log(err);
65}
66
67try {
68  assert.equal(lowestCommonAncestor(tree5, 5, 10), 8);
69
70  console.log(
71    'PASSED: ' + 'assert.equal(lowestCommonAncestor(tree5, 5, 10), 8)'
72  );
73} catch (err) {
74  console.log(err);
75}
76
77function assertIsFunction(f) {
78  return typeof f === 'function';
79}