I have a set $S$ of $n$ (arbitrary) integers which I want to partition into subsets $S_1, \dots, S_k$, each of size $n/k$ (you can assume that $k$ divides $n$). Let $A$ be the arithmetic mean of elements of the set $S$. I am looking for the fastest algorithm that fills each $S_i$ with elements of $S$ such that sum of the elements of each $S_i$ is as close as possible to $A$. Essentially, this is a multi-objective minimization problem and I am looking for Pareto-minimal solutions. The complexity of the brute-force algorithm is $O(n!)$. I am wondering if there exists a faster algorithm.