3689. Maximum Total Subarray Value I

You are given an integer array nums of length n and an integer k. You need to choose exactly k non-empty subarrays nums[l..r] of nums. Subarrays may overlap, and the exact same subarray (same l and r) can be chosen more than once. The value of a subarray nums[l..r] is defined as: max(nums[l..r]) - min(nums[l..r]). The total value is the sum of the values of all chosen subarrays. Return the max