1588 - Sum of All Odd Length Subarrays.

Easy

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