LeetCode: Count Binary Substrings Solution

1/*
2  group and count contiguous 0s/1s
3    "00110011"
4    => [2, 2, 2, 2]
5
6  sum of the minimum adjacent pairs
7    [2, 2, 2, 2]
8    => 2 + 2 + 2 = 6
9*/
10
11/**
12 * @param {string} s
13 * @return {number}
14 */
15var countBinarySubstrings = function (s) {
16  // group and count contiguous 0s/1s
17  const groups = [1]
18  for (let i = 1; i < s.length; i++) {
19    if (s[i] === s[i - 1]) {
20      groups[groups.length - 1]++
21    } else {
22      groups.push(1)
23    }
24  }
25
26  // sum of the minimum adjacent
27  let res = 0
28  for (let i = 0; i < groups.length - 1; i++) {
29    res += Math.min(groups[i], groups[i + 1])
30  }
31
32  return res
33}