The lowest possible difference can be obtained when the sum of the first n elements in the resultant array is minimum, and the sum of the next n elements is maximum.

For every index i, think about how you can find the minimum possible sum of n elements with indices lesser or equal to i, if possible.

Similarly, for every index i, try to find the maximum possible sum of n elements with indices greater or equal to i, if possible.

Now for all indices, check if we can consider it as the partitioning index and hence find the answer.