Merge pull request vJechsmayr#350 from LenartBucar/master

vJechsmayr · web-flow · commit b5f6c1b2ffde · 2020-10-06T11:13:42.000+02:00
Closes vJechsmayr#344
diff --git a/LeetCode/0098_Validate_Binary_Search_Tree.py b/LeetCode/0098_Validate_Binary_Search_Tree.py
@@ -0,0 +1,16 @@
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+
+class Solution:
+    def isValidBST(self, root: TreeNode, sm=[], gt=[]) -> bool:
+        if root is None:
+            return True
+        
+        if any([root.val <= x for x in sm]) or any([root.val >= x for x in gt]):
+            return False
+        
+        return (root.left is None or self.isValidBST(root.left, sm, gt + [root.val])) and (root.right is None or self.isValidBST(root.right, sm + [root.val], gt))
