Day 44.1.txt

1588. Sum of All Odd Length Subarrays

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



class Solution {
    public int sumOddLengthSubarrays(int[] a) {
        int i,j,s=0,n,k,y=0;
        n=a.length%2==0 ? a.length-1 : a.length;
        for(k=0;k<n;k+=2)
        {
            for(i=0,y=0;i<a.length-k;i=y+1,y++)
            {
                for(j=0;j<=k;j++)
                {
                    s=s+a[i];
                    i++;
                }
            }
        }
        return s;
    }
}