You are given an array of integers nums with length n, and a positive odd integer k. Select exactly k disjoint subarrays sub1, sub2, ..., subk from nums such that the last element of subi appears before the first element of sub{i+1} for all 1 <= i <= k-1. The goal is to maximize their combined strength. The strength of the selected subarrays is defined as: strength = k * sum(sub1)- (k - 1) * sum(sub2) + (k - 2) * sum(sub3) - ... - 2 * sum(sub{k-1}) + sum(subk) where sum(subi) is the sum of the elements in the i-th subarray. Return the maximum possible strength that can be obtained from selecting exactly k disjoint subarrays from nums. Note that the chosen subarrays don't need to cover the entire array.