Minimum Difference in Sums After Removal of Elements

Given an array of length 3n, remove exactly n elements so the remaining 2n elements (split into the first n and last n) have the smallest possible difference between their sums. The challenge is to choose which elements to remove, typically solved by scanning possible middle split points and using heap-based prefix/suffix greedy computations to precompute the best n-element sums on each side and minimize their difference.