public class GroupSum0 {
    public static boolean findgroup(int[] values, int pos, int sum) {
        if(sum == 0)
            return true;
        if(pos >= values.length)
            return false;

        int val = values[pos];
        boolean res = findgroup(values, pos+1, sum - val);
        if(res)
            return true;
        return findgroup(values, pos+1, sum);
    }

    public static boolean findgroup(int[] values, int sum) {
        return findgroup(values, 0, sum);
    }

    public static void main(String[] args) {

        assert(findgroup(new int[]{1,3,5,2,7},9) == true);
        assert(findgroup(new int[]{11,3,5,20,7},109) == false);
        for(int n=0;n<25;n++)
            System.out.printf("%d -> %s%n", n, findgroup(new int[]{11,3,5,20,7},n));
    }
}