Fast factoring algorithms? [closed]

Answer 1

public static Integer[] findFactors(int d)
{
    List list = new ArrayList();
    for(int i = 1; i <= d/2; i++)
    {
        if(d % i == 0) list.add(new Integer(i));
    }
    list.add(new Integer(d));
    return (Integer[]) list.toArray(new Integer[0]);
}

public static void main(String[] args)
{
    Integer[] list = findFactors(20);
    for(Integer i : list) System.out.println(i);
}

Output:

1
2
4
5
10
20