# 1588. Sum of All Odd Length Subarrays

<https://leetcode.com/problems/sum-of-all-odd-length-subarrays>

## Description

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`

## ac

```java
```