3427 - Sum of Variable Length Subarrays.

Easy

You are given an integer array nums of size n. For each index i where 0 <= i < n, define a non-empty subarrays nums[start ... i] where start = max(0, i - nums[i]).

Return the total sum of all elements from the subarray defined for each index in the array.

Example 1:

Input: nums = 2,3,1

Output: 11

Explanation:

i

Subarray

Sum

0

nums[0] = [2]

2

1

nums[0 ... 1] = [2, 3]

5

2

nums[1 ... 2] = [3, 1]

4

Total Sum

11

The total sum is 11. Hence, 11 is the output.

Example 2:

Input: nums = 3,1,1,2

Output: 13

Explanation:

i

Subarray

Sum

0

nums[0] = [3]

3

1

nums[0 ... 1] = [3, 1]

4

2

nums[1 ... 2] = [1, 1]

2

3

nums[1 ... 3] = [1, 1, 2]

4

Total Sum

13

The total sum is 13. Hence, 13 is the output.

Constraints:

• 1 <= n == nums.length <= 100

• 1 <= nums[i] <= 1000