1
var subarraySum = function (nums, k) {
2
  const obj = {};
3
  let res = 0;
4
  let sum = 0;
5

6
  for (let i = 0; i < nums.length; i++) {
7
    sum += nums[i];
8
    if (sum == k) res++;
9

10
    if (obj[sum - k]) res += obj[sum - k];
11

12
    obj[sum] ? (obj[sum] += 1) : (obj[sum] = 1);
13
  }
14
  return res;
15
};