Find the sum of the maximum of all subarrays multiplied by their length in O(n).
For example, given an array arr = [4,2,1,2], the output should be 59.

Complete the function sumOfMaxOfSubarrays
sumOfMaxOfSubarrays has the following parameter:
int[] arr: an array of integers

Returns
long integer: the sum of the maximum of all subarrays multiplied by their length

Example:
Input: arr = [4, 2, 1, 2]
Output: 59
Explanation:
Here's how the sum is calculated:
[4] 1 4 1 * 4 = 4
[4, 2] 2 4 2 * 4 = 8
[4, 2, 1] 3 4 3 * 4 = 12
[4, 2, 1, 2] 4 4 4 * 4 = 16
[2] 1 2 1 * 2 = 2
[2, 1] 2 2 2 * 2 = 4
[2, 1, 2] 3 2 3 * 2 = 6
[1] 1 1 1 * 1 = 1
[1, 2] 2 2 2 * 2 = 4
[2] 1 2 1 * 2 = 2
Sum == 59