feature: range sum of bst

trees/RangeSumOfBST.py

@@ -0,0 +1,18 @@
+from typing import Optional
+
+from trees.TreeNode import TreeNode
+
+
+# O(n) time || O(h) space
+# n - number of all nodes
+# h - height of tree
+def range_sum_bst(self, root: Optional[TreeNode], low: int, high: int) -> int:
+    if not root:
+        return 0
+
+    if root.val < low:
+        return range_sum_bst(self, root.right, low, high)
+    elif root.val > high:
+        return range_sum_bst(self, root.left, low, high)
+
+    return root.val + range_sum_bst(self, root.left, low, high) + range_sum_bst(self, root.right, low, high)

trees/test/test_range_sum_bst.py

@@ -0,0 +1,43 @@
+import unittest
+
+from trees.RangeSumOfBST import range_sum_bst
+from trees.TreeNode import TreeNode
+
+
+class MyTestCase(unittest.TestCase):
+    def test_range_sum_bst(self):
+        root = TreeNode(
+            val=10,
+            left=TreeNode(
+                val=5,
+                left=TreeNode(val=3),
+                right=TreeNode(val=7)
+            ),
+            right=TreeNode(
+                val=15,
+                right=TreeNode(18)
+            )
+        )
+
+        self.assertEqual(32, range_sum_bst(self, root, 7, 15))
+
+    def test_range_sum_bst_1(self):
+        root = TreeNode(
+            val=10,
+            left=TreeNode(
+                val=5,
+                left=TreeNode(val=3, left=TreeNode(1)),
+                right=TreeNode(val=7, left=TreeNode(6))
+            ),
+            right=TreeNode(
+                val=15,
+                left=TreeNode(13),
+                right=TreeNode(18)
+            )
+        )
+
+        self.assertEqual(23, range_sum_bst(self, root, 6, 10))
+
+
+if __name__ == '__main__':
+    unittest.main()