@Test
public void testFirstEmpty() {
Collection<String> collection = new HashSet<String>();
assertTrue(Groups.first(collection) == null);
collection.add("Hello World");
assertTrue(Groups.first(collection).equals("Hello World"));
collection.add("Goodbye World");
assertTrue(collection.contains(Groups.first(collection)));
}
public Action choose(LightsOut.Player actor, Set<Action> options) {
if (presses == null) {
presses = new HashSet<Location>();
// linear algebra solution
boolean[][] state = actor.state();
boolean[] s = stateVector(state);
boolean[][] M = stateMatrix(state[0].length, state.length);
gauss(M, s);
// translate to locations
Location[][] locations = actor.locations();
for (int x = 0; x < s.length; x++) {
if (s[x]) {
presses.add(locations[x / state.length][x % state[0].length]);
}
}
}
Location next = Groups.first(presses);
presses.remove(next);
for (Action action : Groups.ofType(LightsOut.Move.class, options)) {
if (((LightsOut.Move) action).target.location().equals(next)) {
return action;
}
}
return null;
}