adding algo

src/my_project/interviews/top_150_questions_round_20/symmetric_tree.py

@@ -0,0 +1,32 @@
+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 isSymmetric(self, root: TreeNode) -> bool:
+        return self.check_mirror(root1=root, root2=root) 
+
+    def check_mirror(self, root1: TreeNode, root2: TreeNode):
+
+        if root1 is None and root2 is None: 
+            return True 
+        elif root1 is not None and root2 is not None:
+            try: 
+                root1.val 
+                root2.val
+            except:
+                return False 
+
+            if root1.val != root2.val: 
+                return False 
+            else:
+                return self.check_mirror(root1.left, root2.right) \
+                       and self.check_mirror(root1.right, root2.left)   
+        else: 
+            return False 

tests/test_150_questions_round_20/test_symmetric_tree_round_20.py

@@ -0,0 +1,15 @@
+import unittest
+from src.my_project.interviews.top_150_questions_round_20\
+.symmetric_tree import TreeNode, Solution
+
+class SymmetricTreeTestCase(unittest.TestCase):
+
+    def test_is_symmetric(self):
+        solution = Solution()
+        output = solution.isSymmetric(TreeNode(1, TreeNode(7), TreeNode(7)))
+        self.assertTrue(output)
+
+    def test_is_no_symmetric(self):
+        solution = Solution()
+        output = solution.isSymmetric(TreeNode(1, TreeNode(2), TreeNode(3)))
+        self.assertFalse(output)