You are given two integer arrays, arr1 and arr2, each of size $n$. You are also given an integer k. Your task is to return the k largest sum combinations that can be formed by adding one element from arr1 and one element from arr2, for all possible pairs (arr1[i] + arr2[j]), where $0 ≤ i, j < n$.

Note: The output should be sorted in non-increasing order.

Constraints:

• $1 ≤ n ≤ 1000$

• $1\leq$ arr1[i], arr2[i] $\leq 10^3$

• $1 ≤$ k $≤ n$