Sum of All Odd Length Subarrays

给一个数组, 求奇数(包括1)size的子数组的合.

class Solution {
    public int sumOddLengthSubarrays(int[] arr) {
        int res = 0;
        for(int size = 1; size <= arr.length; size+=2){
            int i = 0;
            while(i + size - 1 < arr.length) {
                res += getSum(arr, i, i+size - 1);
                i++;
            }
        } 
        return res;
    }
    public int getSum(int[] arr, int start, int end) {
        int sum = 0;
        for(int i = start; i <= end; i++) {
            sum += arr[i];
        }
        return sum;
    }
}