Given an array of positive integers `arr`, calculate the sum of all possible odd-length subarrays.

A subarray is a contiguous subsequence of the array.

Return the sum of all odd-length subarrays of `arr`.

Example 1:

    Input: arr = [1,4,2,5,3]
    Output: 58
    Explanation: The odd-length subarrays of arr and their sums are:
    [1] = 1
    [4] = 4
    [2] = 2
    [5] = 5
    [3] = 3
    [1,4,2] = 7
    [4,2,5] = 11
    [2,5,3] = 10
    [1,4,2,5,3] = 15
    If we add all these together we get 1 + 4 + 2 + 5 + 3 + 7 + 11 + 10 + 15 = 58

Example 2:

    Input: arr = [1,2]
    Output: 3
    Explanation: There are only 2 subarrays of odd length, [1] and [2]. Their sum is 3.

Example 3:

    Input: arr = [10,11,12]
    Output: 66

Constraints:

- `1 <= arr.length <= 100`
- `1 <= arr[i] <= 1000`