def _alpha_beta_search(game: MancalaEnv, alpha=-np.inf, beta=np.inf, depth=5):
"""Search game to determine best action; use alpha-beta pruning.
This version cuts off search and uses an evaluation function."""
if depth == 0 or game.is_game_over():
return game.get_player_utility()
if game.side_to_move == Side.SOUTH:
v = -np.inf
for (_, new_s) in game.next_states():
v = max(v, AlphaBeta._alpha_beta_search(new_s, alpha, beta, depth - 1))
alpha = max(alpha, v)
# if beta <= alpha:
# break
else:
v = np.inf
for (_, new_s) in game.next_states():
v = min(v, AlphaBeta._alpha_beta_search(new_s, alpha, beta, depth - 1))
beta = min(beta, v)
# if beta <= alpha:
# break
return v
class TestMancalaGameState(unittest.TestCase):
def setUp(self):
self.game = MancalaEnv()
def test_initial_state_is_correct(self):
self.assertEqual(self.game.side_to_move, Side.SOUTH)
self.assertFalse(self.game.north_moved)
for hole in range(1, self.game.board.holes + 1):
self.assertEqual(self.game.board.get_seeds(Side.SOUTH, hole), 7)
self.assertEqual(self.game.board.get_seeds(Side.NORTH, hole), 7)
self.assertEqual(self.game.board.get_seeds_in_store(Side.SOUTH), 0)
self.assertEqual(self.game.board.get_seeds_in_store(Side.NORTH), 0)
def test_cloning_immutability(self):
clone = MancalaEnv.clone(self.game)
self.game.perform_move(Move(Side.SOUTH, 3))
self.assertEqual(clone.board.get_seeds(Side.SOUTH, 3), 7)
self.assertEqual(clone.side_to_move, Side.SOUTH)
def test_move_has_required_effects(self):
self.game.perform_move(Move(Side.SOUTH, 5))
self.assertEqual(self.game.board.get_seeds(Side.SOUTH, 5), 0)
self.assertEqual(self.game.board.get_seeds(Side.SOUTH, 6), 8)
self.assertEqual(self.game.board.get_seeds(Side.SOUTH, 7), 8)
self.assertEqual(self.game.board.get_seeds_in_store(Side.SOUTH), 1)
self.assertEqual(self.game.board.get_seeds(Side.NORTH, 1), 8)
self.assertEqual(self.game.board.get_seeds(Side.NORTH, 2), 8)
self.assertEqual(self.game.board.get_seeds(Side.NORTH, 3), 8)
self.assertEqual(self.game.board.get_seeds(Side.NORTH, 4), 8)
self.game.perform_move(Move(Side.NORTH, 4))
self.assertEqual(self.game.board.get_seeds(Side.NORTH, 4), 0)
self.assertEqual(self.game.board.get_seeds(Side.NORTH, 5), 8)
self.assertEqual(self.game.board.get_seeds(Side.NORTH, 6), 8)
self.assertEqual(self.game.board.get_seeds(Side.NORTH, 7), 8)
self.assertEqual(self.game.board.get_seeds_in_store(Side.NORTH), 1)
self.assertEqual(self.game.board.get_seeds(Side.SOUTH, 1), 8)
self.assertEqual(self.game.board.get_seeds(Side.SOUTH, 2), 8)
self.assertEqual(self.game.board.get_seeds(Side.SOUTH, 3), 8)
def test_game_is_over_returns_false(self):
self.assertFalse(self.game.is_game_over())
def test_game_is_over_returns_true(self):
board = self.game.board
for hole in range(1, board.holes + 1):
board.set_seeds(Side.SOUTH, hole, 0)
board.set_seeds_in_store(Side.SOUTH, 49)
self.assertTrue(self.game.is_game_over())
def test_game_returns_winner_the_player_with_most_seeds(self):
board = self.game.board
for hole in range(1, self.game.board.holes + 1):
board.set_seeds(Side.SOUTH, hole, 0)
board.set_seeds(Side.NORTH, hole, 0)
board.set_seeds_in_store(Side.SOUTH, 23)
board.set_seeds_in_store(Side.NORTH, 21)
self.assertEqual(self.game.get_winner(), Side.SOUTH)
def test_game_returns_no_winner_if_players_have_equal_number_of_seeds(self):
board = self.game.board
for hole in range(1, self.game.board.holes + 1):
board.set_seeds(Side.SOUTH, hole, 0)
board.set_seeds(Side.NORTH, hole, 0)
board.set_seeds_in_store(Side.SOUTH, 30)
board.set_seeds_in_store(Side.NORTH, 30)
self.assertEqual(self.game.get_winner(), None)
def test_is_legal_move_returns_true_for_the_pie_rule(self):
board = self.game.board
MancalaEnv.make_move(board, Move(Side.SOUTH, 6), False)
self.assertTrue(MancalaEnv.is_legal_action(board, Move(Side.NORTH, 0), False))
def test_is_legal_move_returns_true_for_the_pie_rule2(self):
env = MancalaEnv()
env.perform_move(Move(Side.SOUTH, 5))
self.assertTrue(env.is_legal(Move(Side.NORTH, 0)))
def test_legal_moves_contains_all_moves(self):
self.assertEqual(len(set(self.game.get_legal_moves())), 7)
self.game.perform_move(Move(Side.SOUTH, 3))
self.assertEqual(len(set(self.game.get_legal_moves())), 8)
def test_side_to_move_doesnt_change(self):
self.game.perform_move(Move(Side.SOUTH, 1))
self.assertEqual(self.game.side_to_move, Side.NORTH)
def test_alphbeta(self):
board = self.game.board
for hole in range(1, self.game.board.holes + 1):
board.set_seeds(Side.SOUTH, hole, 0)
board.set_seeds(Side.NORTH, hole, 0)
board.set_seeds_in_store(Side.SOUTH, 0)
board.set_seeds_in_store(Side.NORTH, 0)
board.set_seeds(Side.SOUTH, 3, 1)
board.set_seeds(Side.SOUTH, 2, 4)
board.set_seeds_op(Side.SOUTH, 4, 5)
print(self.game)
print(search_action(self.game))