1
const binarySearch = (arr, target) => {
2
  let left = 0;
3
  let right = arr.length - 1;
4

5
  while (left <= right) {
6
    const mid = Math.floor((left + right) / 2);
7
    if (arr[mid] === target) {
8
      return mid;
9
    }
10
    if (arr[mid] < target) {
11
      left = mid + 1;
12
    } else {
13
      right = mid - 1;
14
    }
15
  }
16

17
  return left;
18
};
19

20
var maxEnvelopes = function (envelopes) {
21
  envelopes.sort((a, b) => (a[0] === b[0] ? b[1] - a[1] : a[0] - b[0]));
22
  const sub = [envelopes[0][1]];
23

24
  for (let envelope of envelopes) {
25
    if (envelope[1] > sub[sub.length - 1]) {
26
      sub.push(envelope[1]);
27
    } else {
28
      const replaceIndex = binarySearch(sub, envelope[1]);
29
      sub[replaceIndex] = envelope[1];
30
    }
31
  }
32

33
  return sub.length;
34
};