1var assert = require('assert');
2
3function mergeIntervals(ranges) {
4  ranges.sort(function (a, b) {
5    return a[0] - b[0] || a[1] - b[1];
6  });
7
8  let result = [],
9    last;
10
11  ranges.forEach(function (r) {
12    if (!last || r[0] > last[1]) {
13      last = r;
14      result.push(last);
15    } else if (r[1] > last[1]) last[1] = r[1];
16  });
17
18  return result;
19}
20
21// console.log(mergeIntervals([[1, 3], [2, 9], [3, 10], [1, 16]]))
22
23try {
24  assertIsFunction(mergeIntervals, '`mergeIntervals` is a function');
25
26  console.log('PASSED: ' + '`mergeIntervals` is a function');
27} catch (err) {
28  console.log(err);
29}
30
31try {
32  assert.deepEqual(
33    mergeIntervals([
34      [1, 4],
35      [2, 5],
36      [7, 10],
37      [12, 16],
38    ]),
39    [
40      [1, 5],
41      [7, 10],
42      [12, 16],
43    ]
44  );
45
46  console.log(
47    'PASSED: `mergeIntervals([[1, 4], [2, 5], [7, 10], [12, 16]])` should return `[[1, 5], [7, 10], [12, 16]]`'
48  );
49} catch (err) {
50  console.log(err);
51}
52
53try {
54  assert.deepEqual(
55    mergeIntervals([
56      [1, 3],
57      [2, 9],
58      [3, 10],
59      [1, 16],
60    ]),
61    [[1, 16]]
62  );
63
64  console.log(
65    'PASSED: `mergeIntervals([[1, 3], [2, 9], [3, 10], [1, 16]])` should return `[[1, 16]]`'
66  );
67} catch (err) {
68  console.log(err);
69}
70
71function assertIsFunction(f) {
72  return typeof f === 'function';
73}