Permutation of array

Question

For example I have this array:

int a[] = new int[]{3,4,6,2,1};

I need list of all permutations such that if one is like this, {3,2,1

Answer 1

Do like this...

import java.util.ArrayList;
import java.util.Arrays;

public class rohit {

    public static void main(String[] args) {
        ArrayList a=new ArrayList();
        ArrayList b=new ArrayList();
        b.add(1);
        b.add(2);
        b.add(3);
        permu(a,b);
    }

    public static void permu(ArrayList prefix,ArrayList value) {
        if(value.size()==0) {
            System.out.println(prefix);
        } else {
            for(int i=0;i a=new ArrayList();
                a.addAll(prefix);
                a.add(value.get(i));

                ArrayList b=new ArrayList();

                b.addAll(value.subList(0, i));
                b.addAll(value.subList(i+1, value.size()));

                permu(a,b);
            }
        }
    }

}