CheckValidityBST Solution uploaded!

Author: sushant097

coding_solutions/DataStructure_related/Tree/CheckValidityBST.py

@@ -0,0 +1,20 @@
+
+
+# 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: Optional[TreeNode]) -> bool:
+        # Time: O(n)
+        def valid(node, left, right):
+            if not node:
+                return True
+            if not (node.val < right and node.val > left):
+                return False
+            return (valid(node.left, left, node.val) and 
+                    valid(node.right, node.val, right))
+        return valid(root, float("-inf"), float("inf"))
+