Do a better RandomizedSet

leetcode/stuff.py

@@ -396,7 +396,7 @@ def h_index(citations: list[int]) -> int:
     return last_qualified or 0
 
 
-class RandomizedSet:
+class SlowRandomizedSet:
     def __init__(self):
         self._i: set[int] = set()
 
@@ -412,4 +412,36 @@ class RandomizedSet:
         return False
 
     def getRandom(self) -> int:
-        return next(iter(sorted(list(self._i), key=lambda _: random.random())))
+        return random.choice(list(self._i))
+
+
+class RandomizedSet:
+    def __init__(self):
+        self._l: list[int] = []
+        self._m: dict[int, int] = {}
+
+    def insert(self, val: int) -> bool:
+        if val in self._m:
+            return False
+
+        self._m[val] = len(self._l)
+        self._l.append(val)
+
+        return True
+
+    def remove(self, val: int) -> bool:
+        if val not in self._m:
+            return False
+
+        val_loc = self._m[val]
+        last_val = self._l[-1]
+        self._l[val_loc] = last_val
+        self._m[last_val] = val_loc
+
+        self._l.pop()
+        self._m.pop(val)
+
+        return True
+
+    def getRandom(self) -> int:
+        return random.choice(self._l)

leetcode/test_stuff.py

@@ -333,8 +333,15 @@ def test_h_index(citations: list[int], expected: int):
     assert stuff.h_index(citations) == expected
 
 
-def test_randomized_set():
-    inst = stuff.RandomizedSet()
+@pytest.mark.parametrize(
+    ("cls",),
+    [
+        (stuff.SlowRandomizedSet,),
+        (stuff.RandomizedSet,),
+    ],
+)
+def test_randomized_set(cls: type[stuff.RandomizedSet] | type[stuff.SlowRandomizedSet]):
+    inst = cls()
 
     assert inst.insert(1) is True
     assert inst.remove(2) is False
@@ -344,7 +351,7 @@ def test_randomized_set():
     assert inst.insert(2) is False
     assert inst.getRandom() == 2
 
-    inst = stuff.RandomizedSet()
+    inst = cls()
 
     assert inst.insert(1) is True
     assert inst.insert(10) is True
@@ -353,7 +360,31 @@ def test_randomized_set():
 
     seen: set[int] = set()
 
-    for _ in range(100_000):
+    for _ in range(10_000):
         seen.add(inst.getRandom())
 
     assert seen == {1, 10, 20, 30}
+
+    # ["remove","remove","insert","getRandom","remove","insert"]
+    # [[0],[0],[0],[],[0],[0]]
+
+    inst = cls()
+
+    assert inst.remove(0) is False
+    assert inst.remove(0) is False
+    assert inst.insert(0) is True
+    assert inst.getRandom() == 0
+    assert inst.remove(0) is True
+    assert inst.insert(0) is True
+
+    # ["RandomizedSet","insert","insert","remove","insert","remove","getRandom"]
+    # [[],[0],[1],[0],[2],[1],[]]
+
+    inst = cls()
+
+    assert inst.insert(0) is True
+    assert inst.insert(1) is True
+    assert inst.remove(0) is True
+    assert inst.insert(2) is True
+    assert inst.remove(1) is True
+    assert inst.getRandom() == 2