How to iteratively generate k elements subsets from a set of size n in java?

Question

I\'m working on a puzzle that involves analyzing all size k subsets and figuring out which one is optimal. I wrote a solution that works when the number of subsets is small,

Answer 1

You can use org.apache.commons.math3.util.Combinations.

Example:

import java.util.Arrays;
import java.util.Iterator;

import org.apache.commons.math3.util.Combinations;

public class tmp {
    public static void main(String[] args) {
        for (Iterator<int[]> iter = new Combinations(5, 3).iterator(); iter.hasNext();) {
            System.out.println(Arrays.toString(iter.next()));
        }
    }

}

Output: [0, 1, 2] [0, 1, 3] [0, 2, 3] [1, 2, 3] [0, 1, 4] [0, 2, 4] [1, 2, 4] [0, 3, 4] [1, 3, 4] [2, 3, 4]