Create range-sum-of-bst.py

Author: kamyu104

Python/range-sum-of-bst.py

@@ -0,0 +1,31 @@
+# Time:  O(n)
+# Space: O(h)
+
+# Definition for a binary tree node.
+class TreeNode(object):
+    def __init__(self, x):
+        self.val = x
+        self.left = None
+        self.right = None
+
+
+class Solution(object):
+    def rangeSumBST(self, root, L, R):
+        """
+        :type root: TreeNode
+        :type L: int
+        :type R: int
+        :rtype: int
+        """
+        result = 0
+        s = [root]
+        while s:
+            node = s.pop()
+            if node:
+                if L <= node.val <= R:
+                    result += node.val
+                if L < node.val:
+                    s.append(node.left)
+                if node.val < R:
+                    s.append(node.right)
+        return result