// enumerate the different combinations // for select k objects from the set of objects given in list L public static List> comb(List L, int k) { if (k == 0) return new ArrayList>(){{add(new ArrayList( ));}}; if (L.size() == k) return new ArrayList>(){{add(new ArrayList(L));}}; List> L1 = comb(L.subList(1,L.size()),k); List> L2 = comb(L.subList(1,L.size()),k-1); for (List list : L2) list.add(L.get(0)); L1.addAll(L2); return L1; }

Q.Study the given Java codes. Explain in plain English the logic for enumerating combinations of a certain size for a given set.