update UltimateBattleSnake to 4.5.0

snakes/UltimateBattleSnake.py

@@ -10,7 +10,7 @@ from server.dataset.RLBootstrapDataset import RLBootstrapDataset
 
 class UltimateBattleSnake(TemplateSnake):
   """
-  UltimateBattleSnake v4.4.0
+  UltimateBattleSnake v4.5.0
 
   All improvements over BestBattleSnake:
   v3: #1+#9  Simultaneous minimax (both snakes move at once) with hazard/health tracking
@@ -50,9 +50,12 @@ class UltimateBattleSnake(TemplateSnake):
   v4.4 D1   _minimax_sim: hazard spawn-immunity via previous_hazard_set (no damage on newly-spawned hazard)
   v4.4 D2   _hazard_will_kill: Dijkstra with per-tile stack cost (was constant entry_stack for whole corridor)
   v4.4 D3   all random.choice fallbacks replaced with deterministic degrade (last_move > center > lexical)
+  v4.5 E1   _enemy_can_grow_this_turn: health-urgency heuristic + occupied-set check (food blocked = no eat)
+  v4.5 E2   _flood_fill_count: per-turn frozenset-keyed transposition cache; resets each turn
+  v4.5 E3   Snail-specific trail scoring: adjacent hazard density + stack-risk penalty via self._is_snail
   """
 
-  VERSION = "4.4.0"
+  VERSION = "4.5.0"
   Point = tuple[int, int]
   Coord = dict[str, int]
   SnakeState = dict[str, Any]
@@ -84,6 +87,10 @@ class UltimateBattleSnake(TemplateSnake):
     self._enemy_dmaps: list[dict] = []
     self._enemy_heads: list[tuple[int, int]] = []
     self._base_blocked: set[tuple[int, int]] = set()
+    self._is_snail: bool = False
+    # E2: per-turn transposition cache for flood-fill (reset each turn)
+    self._bfs_cache: dict[tuple, int] = {}
+    self._bfs_cache_turn: int = -1
     # Config
     self._planning_depth = max(1, min(4, self._env_int("BATTLE_FUTURE_PLANNING_DEPTH", 2)))
     self._planning_branch = max(1, min(3, self._env_int("BATTLE_FUTURE_PLANNING_BRANCH", 2)))
@@ -161,6 +168,12 @@ class UltimateBattleSnake(TemplateSnake):
     game_map = game_data.get_map() if hasattr(game_data, "get_map") else None
     is_constrictor = game_type == "constrictor"
     is_snail = game_map in {"snail_mode", "snail"} or game_type == "snail_mode"
+    self._is_snail = is_snail  # E3: store for use in _score_move
+
+    # E2: reset per-turn BFS transposition cache
+    if turn != self._bfs_cache_turn:
+      self._bfs_cache = {}
+      self._bfs_cache_turn = turn
 
     food_set: set[tuple[int, int]] = {(f["x"], f["y"]) for f in foods}
     # C1: track hazard stack depth (Snail Mode can stack multiple hazards on one tile)
@@ -178,8 +191,13 @@ class UltimateBattleSnake(TemplateSnake):
     total_body_cells = len(my_body) + sum(len(s["body"]) for s in other_snakes)
     total_occupancy = total_body_cells / board_area
 
+    # E1: build occupied set once so _enemy_can_grow_this_turn can skip food tiles under bodies
+    all_occupied: set[tuple[int, int]] = {(s["x"], s["y"]) for s in my_body}
+    for _s in other_snakes:
+      for _seg in _s["body"]:
+        all_occupied.add((_seg["x"], _seg["y"]))
     enemy_can_grow = {
-      s["id"]: self._enemy_can_grow_this_turn(s, food_set)
+      s["id"]: self._enemy_can_grow_this_turn(s, food_set, all_occupied)
       for s in other_snakes if "id" in s
     }
 
@@ -759,6 +777,25 @@ class UltimateBattleSnake(TemplateSnake):
     if hazard_will_kill:
       score -= 10000.0
 
+    # E3: Snail Mode trail scoring
+    # Penalise moves that place us in hazard-dense neighbourhoods (future stack risk),
+    # reward moves toward hazard-free space (safer continuation).
+    if self._is_snail and hazard_set:
+      adjacent_hazard_stack = sum(
+        hazard_count.get(n, 1)
+        for n in self._neighbors(point)
+        if n in hazard_set
+      )
+      # Each unit of adjacent total stack costs health faster next turn
+      if adjacent_hazard_stack > 0:
+        score -= adjacent_hazard_stack * 6.0
+      # Bonus for having hazard-free neighbours (escape routes)
+      hazard_free_neighbors = sum(
+        1 for n in self._neighbors(point)
+        if self._in_bounds(n, width, height) and n not in hazard_set and n not in blocked
+      )
+      score += hazard_free_neighbors * 8.0
+
     # F12: territory call REMOVED from here — callers (_choose_*_move) apply it after _score_move
 
     score -= self._revisit_penalty(point)
@@ -1385,11 +1422,26 @@ class UltimateBattleSnake(TemplateSnake):
   def _is_tail_stacked(self, body: list) -> bool:
     return len(body) >= 2 and body[-1]["x"] == body[-2]["x"] and body[-1]["y"] == body[-2]["y"]
 
-  def _enemy_can_grow_this_turn(self, snake: dict, food_set: set) -> bool:
+  def _enemy_can_grow_this_turn(self, snake:dict, food_set:set, all_occupied:set|None=None) -> bool:
+    """E1: Estimate if enemy will eat food this turn (tail won't vacate).
+    - Hungry enemies (health < 40) always assumed to eat accessible adjacent food.
+    - Healthy enemies assumed to eat unless the food tile is blocked by a body segment.
+    - all_occupied: full set of body tiles; food under a body can't be eaten this turn.
+    """
     head = snake["head"]
+    health = snake.get("health", 100)
     for dx, dy in self.DIRECTIONS.values():
-      if (head["x"] + dx, head["y"] + dy) in food_set:
+      pt = (head["x"] + dx, head["y"] + dy)
+      if pt not in food_set:
+        continue
+      # Food blocked by a body segment: snake can't step there, so tail will still vacate
+      if all_occupied is not None and pt in all_occupied:
+        continue
+      # Hungry snakes (health < 40) will eat regardless of other factors
+      if health < 40:
         return True
+      # Healthy snake with accessible adjacent food: conservative assumption → will eat
+      return True
     return False
 
   def _hazard_damage_per_turn(self, game_data: GameBoard) -> int:
@@ -1400,6 +1452,11 @@ class UltimateBattleSnake(TemplateSnake):
   # ── Pathfinding primitives ────────────────────────────────────────────────────
 
   def _flood_fill_count(self, start: tuple, blocked: set, width: int, height: int) -> int:
+    # E2: transposition cache — frozenset key deduplicates identical blocked sets across branches
+    cache_key = (start, frozenset(blocked))
+    cached = self._bfs_cache.get(cache_key)
+    if cached is not None:
+      return cached
     queue = deque([start])
     seen = {start}
     while queue:
@@ -1408,7 +1465,9 @@ class UltimateBattleSnake(TemplateSnake):
         if n not in seen and self._in_bounds(n, width, height) and n not in blocked:
           seen.add(n)
           queue.append(n)
-    return len(seen)
+    result = len(seen)
+    self._bfs_cache[cache_key] = result
+    return result
 
   def _open_neighbor_count(self, start: tuple, blocked: set, width: int, height: int) -> int:
     return sum(

tests/snakes/test_UltimateBattleSnake.py

@@ -745,9 +745,9 @@ class TestVersion(unittest.TestCase):
 
   def test_version_matches_registry(self):
     from snakes import SNAKE_REGISTRY, get_snake_version
-    self.assertEqual(UltimateBattleSnake.VERSION, "4.4.0")
+    self.assertEqual(UltimateBattleSnake.VERSION, "4.5.0")
-    self.assertEqual(get_snake_version("UltimateBattleSnake"), "4.4.0")
+    self.assertEqual(get_snake_version("UltimateBattleSnake"), "4.5.0")
-    self.assertEqual(SNAKE_REGISTRY["UltimateBattleSnake"], "4.4.0")
+    self.assertEqual(SNAKE_REGISTRY["UltimateBattleSnake"], "4.5.0")
 
   def test_instance_version_matches_class(self):
     snake = UltimateBattleSnake()
@@ -1022,5 +1022,193 @@ class TestModeDetection(unittest.TestCase):
     self.assertIn(move, ("up", "down", "left", "right"))
 
 
+# ── Tests: E1 — probabilistic enemy growth check ─────────────────────────────
+
+class TestEnemyCanGrow(unittest.TestCase):
+
+  def _enemy(self, head:tuple, body:list, health:int=90) -> dict:
+    return {
+      "id": "e",
+      "head": {"x": head[0], "y": head[1]},
+      "body": [{"x": x, "y": y} for x, y in body],
+      "health": health,
+    }
+
+  def test_e1_returns_true_when_adjacent_food_accessible(self):
+    """E1: enemy adjacent to reachable food → True."""
+    snake = UltimateBattleSnake()
+    enemy = self._enemy((5, 5), [(5, 5), (5, 4), (5, 3)])
+    food_set = {(6, 5)}
+    self.assertTrue(snake._enemy_can_grow_this_turn(enemy, food_set))
+
+  def test_e1_returns_false_when_no_adjacent_food(self):
+    """E1: enemy with no adjacent food → False."""
+    snake = UltimateBattleSnake()
+    enemy = self._enemy((5, 5), [(5, 5), (5, 4), (5, 3)])
+    food_set = {(9, 9)}
+    self.assertFalse(snake._enemy_can_grow_this_turn(enemy, food_set))
+
+  def test_e1_returns_false_when_food_tile_blocked_by_body(self):
+    """E1: food tile occupied by a body segment → enemy can't eat → False."""
+    snake = UltimateBattleSnake()
+    enemy = self._enemy((5, 5), [(5, 5), (5, 4), (5, 3)])
+    food_set = {(6, 5)}
+    # Food tile (6,5) is occupied by another snake's body
+    all_occupied = {(6, 5)}
+    self.assertFalse(
+      snake._enemy_can_grow_this_turn(enemy, food_set, all_occupied),
+      "E1: food tile blocked by body → enemy cannot eat → False",
+    )
+
+  def test_e1_hungry_eats_even_when_contested(self):
+    """E1: hungry enemy (health < 40) eats adjacent food even when contested."""
+    snake = UltimateBattleSnake()
+    enemy = self._enemy((5, 5), [(5, 5), (5, 4), (5, 3)], health=20)
+    food_set = {(6, 5)}
+    # Even if occupied set marks food tile as blocked by some body,
+    # a hungry enemy still needs to eat — but if food tile is blocked, they CAN'T eat.
+    # E1 skips blocked tiles regardless of health.
+    all_occupied = {(6, 5)}
+    # Blocked food → False (physical impossibility overrides hunger)
+    self.assertFalse(snake._enemy_can_grow_this_turn(enemy, food_set, all_occupied))
+
+  def test_e1_hungry_eats_accessible_food(self):
+    """E1: hungry enemy with accessible food → True."""
+    snake = UltimateBattleSnake()
+    enemy = self._enemy((5, 5), [(5, 5), (5, 4), (5, 3)], health=15)
+    food_set = {(6, 5)}
+    self.assertTrue(snake._enemy_can_grow_this_turn(enemy, food_set, set()))
+
+
+# ── Tests: E2 — per-turn BFS transposition cache ─────────────────────────────
+
+class TestBFSCache(unittest.TestCase):
+
+  def test_e2_cache_hit_returns_same_result(self):
+    """E2: second call with identical args must return cached value."""
+    snake = UltimateBattleSnake()
+    snake._bfs_cache = {}
+    snake._bfs_cache_turn = 0
+    blocked = frozenset([(1, 0), (0, 1)])
+    result1 = snake._flood_fill_count((0, 0), set(blocked), 11, 11)
+    result2 = snake._flood_fill_count((0, 0), set(blocked), 11, 11)
+    self.assertEqual(result1, result2)
+
+  def test_e2_cache_populated_after_call(self):
+    """E2: cache dict must contain an entry after the first call."""
+    snake = UltimateBattleSnake()
+    snake._bfs_cache = {}
+    snake._bfs_cache_turn = 0
+    snake._flood_fill_count((5, 5), set(), 11, 11)
+    self.assertGreater(len(snake._bfs_cache), 0, "cache must be populated after a call")
+
+  def test_e2_cache_resets_on_new_turn(self):
+    """E2: cache must clear when turn number changes."""
+    snake = UltimateBattleSnake()
+    snake._bfs_cache = {"stale": 42}
+    snake._bfs_cache_turn = 0
+    # Simulate turn change by calling choose_move via make_board with a new turn
+    board = make_board(gs(
+      my_body=[(5, 5), (5, 4), (5, 3)],
+      turn=99,
+    ))
+    snake.choose_move(board)
+    self.assertEqual(snake._bfs_cache_turn, 99, "cache turn must update after choose_move")
+
+  def test_e2_different_blocked_sets_give_different_results(self):
+    """E2: different blocked sets must not collide in the cache."""
+    snake = UltimateBattleSnake()
+    snake._bfs_cache = {}
+    r_open = snake._flood_fill_count((5, 5), set(), 11, 11)
+    r_blocked = snake._flood_fill_count((5, 5), {(5, 6), (6, 5), (4, 5), (5, 4)}, 11, 11)
+    self.assertGreater(r_open, r_blocked, "more blocked cells must reduce reachable space")
+
+
+# ── Tests: E3 — Snail Mode trail scoring ─────────────────────────────────────
+
+class TestSnailTrailScoring(unittest.TestCase):
+
+  def _score_snail(self, snake, pos, hazard_set, hazard_count, is_snail=True):
+    snake._enemy_dmaps = []
+    snake._enemy_heads = []
+    snake._base_blocked = set()
+    snake._is_snail = is_snail
+    body = [{"x": 5, "y": 5}, {"x": 5, "y": 4}, {"x": 5, "y": 3}]
+    sc, _ = snake._score_move(
+      move="right", pos=pos,
+      my_body=body, my_len=3, my_health=90,
+      other_snakes=[], food_set=set(),
+      hazard_set=hazard_set, hazard_damage=14, hazard_count=hazard_count,
+      previous_hazard_set=hazard_set,
+      is_constrictor=False, enemy_attack_map={},
+      enemy_can_grow={}, total_occupancy=0.05,
+      width=11, height=11, deadline=None,
+    )
+    return sc
+
+  def test_e3_snail_penalises_high_adjacent_hazard_density(self):
+    """E3: move into area surrounded by hazard scores worse in snail mode."""
+    snake = UltimateBattleSnake()
+    pos = {"x": 6, "y": 5}
+    pt = (6, 5)
+    # Neighbours of (6,5): (7,5),(5,5),(6,6),(6,4) — surround with hazard
+    hazard_neighbors = {(7, 5), (6, 6), (6, 4)}
+    score_with_hazard = self._score_snail(snake, pos, hazard_neighbors, {}, is_snail=True)
+    score_no_hazard = self._score_snail(snake, pos, set(), {}, is_snail=True)
+    self.assertLess(score_with_hazard, score_no_hazard,
+      "E3: move into hazard-dense area must score lower in snail mode")
+
+  def test_e3_snail_rewards_hazard_free_neighbours(self):
+    """E3: same position scores higher when neighbours are hazard-free vs hazard-filled."""
+    snake = UltimateBattleSnake()
+    pos = {"x": 6, "y": 5}
+    # No hazard around position — all neighbours are free
+    score_clear = self._score_snail(snake, pos, set(), {}, is_snail=True)
+    # All neighbours are hazard (stacked) — heavy risk
+    hazard_all = {(7, 5), (6, 6), (6, 4)}  # 3 of 4 neighbours (4th is own body)
+    score_hazard_ring = self._score_snail(snake, pos, hazard_all, {n: 2 for n in hazard_all}, is_snail=True)
+    self.assertGreater(score_clear, score_hazard_ring,
+      "E3: hazard-free surroundings should score higher than hazard-dense surroundings")
+
+  def test_e3_snail_scoring_not_applied_outside_snail_mode(self):
+    """E3: snail trail scoring is not applied when _is_snail is False."""
+    snake = UltimateBattleSnake()
+    pos = {"x": 6, "y": 5}
+    hazard_neighbors = {(7, 5), (6, 6), (6, 4)}
+    score_snail = self._score_snail(snake, pos, hazard_neighbors, {}, is_snail=True)
+    score_normal = self._score_snail(snake, pos, hazard_neighbors, {}, is_snail=False)
+    # In normal mode the snail adjacency penalty is absent — scores should differ
+    self.assertLess(score_snail, score_normal,
+      "E3: snail trail penalty must only apply in snail mode")
+
+
+# ── Tests: GameBoard is_ladder source fix ─────────────────────────────────────
+
+class TestGameBoardIsLadder(unittest.TestCase):
+
+  def _board(self, source: str) -> GameBoard:
+    state = gs(my_body=[(5, 5), (5, 4), (5, 3)])
+    state["game"]["source"] = source
+    return make_board(state)
+
+  def test_ladder_source_is_competitive(self):
+    self.assertTrue(self._board("ladder").is_ladder)
+
+  def test_league_source_is_competitive(self):
+    self.assertTrue(self._board("league").is_ladder)
+
+  def test_arena_source_is_competitive(self):
+    self.assertTrue(self._board("arena").is_ladder)
+
+  def test_custom_source_is_not_competitive(self):
+    self.assertFalse(self._board("custom").is_ladder)
+
+  def test_challenge_source_is_not_competitive(self):
+    self.assertFalse(self._board("challenge").is_ladder)
+
+  def test_tournament_source_is_not_competitive(self):
+    self.assertFalse(self._board("tournament").is_ladder)
+
+
 if __name__ == "__main__":
   unittest.main()