1
/**
2
 * @param {number[]} nums
3
 * @return {number}
4
 */
5
var triangleNumber = function (nums) {
6
  nums.sort((a, b) => a - b);
7
  let result = 0,
8
    n = nums.length,
9
    i,
10
    j,
11
    k;
12
  for (i = 0; i < n; i++) {
13
    for (j = i + 1, k = j + 1; j < n - 1 && k <= n; ) {
14
      if (k == n || nums[i] + nums[j] <= nums[k]) {
15
        if (k > j + 1) result += k - j - 1;
16
        j++;
17
      } else k++;
18
    }
19
  }
20
  return result;
21
};