1588. Sum of All Odd Length Subarrays

QUESTION:

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
``````

SOLUTION:

``````class Solution {
fun sumOddLengthSubarrays(arr: IntArray): Int {
var result = 0;
for (i in arr.indices) {
var length = 0;
while(i+length<=arr.size-1) {
result+=sum(arr,i,i+length)
length+=2
}
}
return result
}

fun sum(arr: IntArray,start: Int,end:Int) :Int {
var sum = 0
for (i in start..end) {
sum+=arr[i]
}
return sum
}
}
``````