1var assert = require('assert');
2
3function Node(val) {
4  this.val = val;
5  this.left = this.right = null;
6}
7
8function mergeTwoBinaryTrees(tree1, tree2) {
9  if (tree1 == null) {
10    return tree2;
11  }
12  if (tree2 == null) {
13    return tree1;
14  }
15  tree1.val += tree2.val;
16  tree1.left = mergeTwoBinaryTrees(tree1.left, tree2.left);
17  tree1.right = mergeTwoBinaryTrees(tree1.right, tree2.right);
18  return tree1;
19}
20
21function Node(val) {
22  this.val = val;
23  this.left = null;
24  this.right = null;
25}
26
27// Regular binary trees
28var tree1 = new Node(4);
29tree1.left = new Node(1);
30tree1.right = new Node(3);
31
32var tree2 = new Node(5);
33tree2.left = new Node(10);
34tree2.left.left = new Node(17);
35tree2.left.right = new Node(3);
36tree2.right = new Node(8);
37
38// Binary search trees
39var tree3 = new Node(6);
40tree3.left = new Node(3);
41
42var tree4 = new Node(5);
43tree4.left = new Node(3);
44tree4.left.left = new Node(2);
45tree4.left.left.left = new Node(1);
46
47var tree5 = new Node(8);
48tree5.left = new Node(6);
49tree5.right = new Node(9);
50tree5.left.left = new Node(5);
51tree5.left.right = new Node(7);
52tree5.right.right = new Node(10);
53
54try {
55  assertIsFunction(
56    mergeTwoBinaryTrees,
57    '`mergeTwoBinaryTrees` should be a function'
58  );
59
60  console.log('PASSED: ' + '`mergeTwoBinaryTrees` should be a function');
61} catch (err) {
62  console.log(err);
63}
64
65try {
66  var presetMerged = mergeTwoBinaryTrees(tree1, tree2);
67  var mergedTree = new Node(9);
68  mergedTree.left = new Node(11);
69  mergedTree.left.left = new Node(17);
70  mergedTree.left.right = new Node(3);
71  mergedTree.right = new Node(11);
72  assert.deepEqual(presetMerged, mergedTree);
73
74  console.log(
75    'PASSED: `mergeTwoBinaryTrees(tree1, tree2)` should return a merged tree'
76  );
77} catch (err) {
78  console.log(err);
79}
80
81function assertIsFunction(f) {
82  return typeof f === 'function';
83}