"Binary Trees With Factors" solution

Author: lancelote

src/binary_trees_with_factors.py

@@ -0,0 +1,24 @@
+from collections import defaultdict
+
+
+MOD = 10**9 + 7
+
+
+class Solution:
+    def numFactoredBinaryTrees(self, arr: list[int]) -> int:
+        cache: dict[int, int] = defaultdict(int)
+        sorted_arr = sorted(arr)
+
+        for i, x in enumerate(sorted_arr):
+            options = 1
+
+            for j in range(i):
+                if x % sorted_arr[j] == 0:
+                    a = x // sorted_arr[j]
+                    b = x // a
+
+                    options += cache[a] * cache[b]
+
+            cache[x] = options
+
+        return sum(cache.values()) % MOD

tests/test_binary_trees_with_factors.py

@@ -0,0 +1,15 @@
+import pytest
+
+from src.binary_trees_with_factors import Solution
+
+
+@pytest.mark.parametrize(
+    "arr,expected",
+    (
+        ([2, 4], 3),
+        ([2, 4, 5, 10], 7),
+        ([15, 13, 22, 7, 11], 5),
+    ),
+)
+def test_solution(arr, expected):
+    assert Solution().numFactoredBinaryTrees(arr) == expected