@Test
public void testPermutations() {
String[] input = {"A", "B", "C"};
List<String[]> perm = new LinkedList<>();
Backtracker.permutations(input, perm::add);
Iterator<String[]> itr = perm.iterator();
assertArrayEquals(new String[] {"A", "B", "C"}, itr.next());
assertArrayEquals(new String[] {"A", "C", "B"}, itr.next());
assertArrayEquals(new String[] {"B", "A", "C"}, itr.next());
assertArrayEquals(new String[] {"B", "C", "A"}, itr.next());
assertArrayEquals(new String[] {"C", "A", "B"}, itr.next());
assertArrayEquals(new String[] {"C", "B", "A"}, itr.next());
assertFalse(itr.hasNext());
}
@Test
public void testSubsets() {
String[] input = {"A", "B", "C"};
List<String[]> ss = new LinkedList<>();
Backtracker.subsets(input, ss::add);
Iterator<String[]> itr = ss.iterator();
assertArrayEquals(new String[] {"A", "B", "C"}, itr.next());
assertArrayEquals(new String[] {"A", "B"}, itr.next());
assertArrayEquals(new String[] {"A", "C"}, itr.next());
assertArrayEquals(new String[] {"A"}, itr.next());
assertArrayEquals(new String[] {"B", "C"}, itr.next());
assertArrayEquals(new String[] {"B"}, itr.next());
assertArrayEquals(new String[] {"C"}, itr.next());
assertArrayEquals(new String[] {}, itr.next());
assertFalse(itr.hasNext());
}