diff --git a/data_structures/hashing/hash_map.py b/data_structures/hashing/hash_map.py index 9213d6930f67..5d89f807e243 100644 --- a/data_structures/hashing/hash_map.py +++ b/data_structures/hashing/hash_map.py @@ -16,7 +16,7 @@ VAL = TypeVar("VAL") -@dataclass(frozen=True, slots=True) +@dataclass(slots=True) class _Item(Generic[KEY, VAL]): key: KEY val: VAL @@ -72,16 +72,16 @@ def _try_set(self, ind: int, key: KEY, val: VAL) -> bool: If bucket is empty or key is the same, does insert and return True. - If bucket has another key or deleted placeholder, - that means that we need to check next bucket. + If bucket has another key that means that we need to check next bucket. """ stored = self._buckets[ind] if not stored: + # A falsy item means that is None (bucket never used) or _deleted. self._buckets[ind] = _Item(key, val) self._len += 1 return True elif stored.key == key: - self._buckets[ind] = _Item(key, val) + stored.val = val return True else: return False @@ -228,6 +228,25 @@ def __delitem__(self, key: KEY) -> None: Traceback (most recent call last): ... KeyError: 4 + + # Test resize down when sparse + ## Setup: resize up + >>> hm = HashMap(100, capacity_factor=0.75) + >>> len(hm._buckets) + 100 + >>> for i in range(75): + ... hm[i] = i + >>> len(hm._buckets) + 100 + >>> hm[75] = 75 + >>> len(hm._buckets) + 200 + + ## Resize down + >>> del hm[75] + >>> del hm[74] + >>> len(hm._buckets) + 100 """ for ind in self._iterate_buckets(key): item = self._buckets[ind]