1var assert = require('assert');
2
3function swap(arr, first, second) {
4  var temp = arr[first];
5  arr[first] = arr[second];
6  arr[second] = temp;
7}
8
9function dutchNatFlag(arr) {
10  let low = 0;
11  let mid = 0;
12  let high = arr.length - 1;
13
14  while (mid <= high) {
15    if (arr[mid] === 0) {
16      swap(arr, low++, mid++);
17    } else if (arr[mid] === 2) {
18      swap(arr, mid, high--);
19    } else if (arr[mid] === 1) {
20      mid++;
21    }
22  }
23
24  return arr;
25}
26
27dutchNatFlag([2, 2, 2, 0, 0, 0, 1, 1]);
28
29try {
30  assert.deepEqual(dutchNatFlag([2, 0, 1, 0, 2]), [0, 0, 1, 2, 2]);
31
32  console.log(
33    'PASSED: assert.deepEqual(dutchNatFlag([2, 0, 1, 0, 2]), [0, 0, 1, 2, 2]);'
34  );
35} catch (err) {
36  console.log(err);
37}
38
39try {
40  assert.deepEqual(dutchNatFlag([0, 1, 2]), [0, 1, 2]);
41
42  console.log(
43    'PASSED: ' + 'assert.deepEqual(dutchNatFlag([0, 1, 2]), [0, 1, 2]);'
44  );
45} catch (err) {
46  console.log(err);
47}
48
49try {
50  assert.deepEqual(
51    dutchNatFlag([2, 0, 0, 1, 1, 0, 2, 2]),
52    [0, 0, 0, 1, 1, 2, 2, 2]
53  );
54
55  console.log(
56    'PASSED: assert.deepEqual(dutchNatFlag([2, 0, 0, 1, 1, 0, 2, 2]), [0, 0, 0, 1, 1, 2, 2, 2]);'
57  );
58} catch (err) {
59  console.log(err);
60}