Added max-depth

Author: avidLearnerInProgress

max_depth.py

@@ -0,0 +1,13 @@
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, x):
+#         self.val = x
+#         self.left = None
+#         self.right = None
+
+class Solution:
+    def maxDepth(self, root: TreeNode) -> int:
+        if not root:
+            return 0
+        
+        return 1 + max(self.maxDepth(root.left), self.maxDepth( root.right))