Max Sum Three Subarrays

Given an integer array nums and an integer k, select three non-overlapping subarrays each of length k that maximize the sum of their elements. Return the starting indices of these subarrays as a sorted list [a, b, c] (i.e., a < b < c).

If multiple selections yield the same maximum sum, return the lexicographically smallest list of starting indices.

Examples
Input: [1,2,3]
Output: [-1,-1,-1]
Hints

Max Sum Three Subarrays

Given an integer array `nums` and an integer `k`, select **three non-overlapping subarrays** each of length `k` that maximize the sum of their elements. Return the starting indices of these subarrays as a sorted list `[a, b, c]` (i.e., `a < b < c`).