Maximum Sum of Two Non-Overlapping Subarrays

Given an integer array ARR and a positive integer K, your objective is to find two non-overlapping subarrays (contiguous) of length K each, such that their summed total is maximized.

Example:

Input:

ARR = [2, 5, 1, 2, 7, 3, 0]
K = 2

Output:

17

Explanation:

The optimal choice is subarrays [2, 5] and [7, 3], which together yield the maximum sum of 2 + 5 + 7 + 3 = 17.

Constraints:

• 1 <= T <= 10²
• 2 <= N <= 5 * 10³
• 1 <= K <= N / 2
• -10⁵ <= ARR[i] <= 10⁵
• The array will always have at least two non-overlapping subarrays of size K.

Input:

The first line consists of an integer 'T', the number of test cases.
Each test case starts with two integers 'N' and 'K', denoting the size of the array and the subarray length, respectively.
The second line contains 'N' space-separated integers indicating the elements of 'ARR'.

Output:

For each test case, output a single integer indicating the maximum obtainable sum from two non-overlapping subarrays of length 'K'.

Note:

Implement the function as specified; printing is handled separately.