You are given an integer array `nums` and you have to return a new `counts` array. The `counts` array has the property where `counts[i]` is the number of smaller elements to the right of `nums[i]`.

Example 1:

    Input: nums = [5,2,6,1]
    Output: [2,1,1,0]
    Explanation:
    To the right of 5 there are 2 smaller elements (2 and 1).
    To the right of 2 there is only 1 smaller element (1).
    To the right of 6 there is 1 smaller element (1).
    To the right of 1 there is 0 smaller element.

Example 2:

    Input: nums = [-1]
    Output: [0]

Example 3:

    Input: nums = [-1,-1]
    Output: [0,0]

Constraints:

- `1 <= nums.length <= 105`
- `-104 <= nums[i] <= 104`