adding invert binary tree

src/my_project/interviews/top_150_questions_round_11/invert_binary_tree.py

@@ -0,0 +1,23 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC, abstractmethod
+
+class TreeNode:
+    def __init__(self, val=0, left=None, right=None):
+        self.val = val
+        self.left = left
+        self.right = right
+
+class Solution:
+    def invertTree(self, root: TreeNode) -> TreeNode:
+
+        try: 
+            root.val 
+        except: 
+            return root
+
+        root.left, root.right = (
+            self.invertTree(root.right),
+            self.invertTree(root.left)
+        )        
+
+        return root

tests/test_150_questions_round_11/test_invert_binary_tree_round_11.py

@@ -0,0 +1,19 @@
+import unittest
+from src.my_project.interviews.top_150_questions_round_11\
+.invert_binary_tree import TreeNode, Solution
+
+class InvertTreeTestCase(unittest.TestCase):
+
+    def test_none_inverted_tree(self):
+        solution = Solution()
+        tree = None
+        output = solution.invertTree(root=tree)
+        self.assertIsNone(output)
+
+    def test_inverted_tree(self):
+        solution = Solution()
+        tree = TreeNode(1,TreeNode(2),TreeNode(3))
+        output = solution.invertTree(root=tree)
+        self.assertEqual(1,output.val)
+        self.assertEqual(2,output.right.val)
+        self.assertEqual(3,output.left.val)