diff --git a/src/my_project/interviews/amazon_high_frequency_23/common_algos/two_sum_round_5.py b/src/my_project/interviews/amazon_high_frequency_23/common_algos/two_sum_round_5.py
new file mode 100644
index 00000000..edaea7a4
--- /dev/null
+++ b/src/my_project/interviews/amazon_high_frequency_23/common_algos/two_sum_round_5.py
@@ -0,0 +1,17 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC, abstractmethod
+
+class Solution:
+    def twoSum(self, nums: List[int], target: int) -> List[int]:
+
+        answer = dict()
+
+        for k, v in enumerate(nums):
+
+            if v in answer:
+                return [answer[v], k]
+            else: 
+                answer[target - v] = k
+
+        return []
+
diff --git a/src/my_project/interviews/amazon_high_frequency_23/common_algos/valid_palindrome_round_5.py b/src/my_project/interviews/amazon_high_frequency_23/common_algos/valid_palindrome_round_5.py
new file mode 100644
index 00000000..c21f9762
--- /dev/null
+++ b/src/my_project/interviews/amazon_high_frequency_23/common_algos/valid_palindrome_round_5.py
@@ -0,0 +1,22 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC, abstractmethod
+import re
+
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+
+        # To lowercase
+        s = s.lower()
+
+        # Remove non-alphanumeric
+        s = re.sub(pattern=r'[^a-zA-Z0-9]', repl='', string=s)
+
+        # Determine if s is palindrome or not
+        len_s = len(s)
+
+        for i in range(len_s//2):
+
+            if s[i] != s[len_s - 1 - i]:
+                return False 
+            
+        return True 
\ No newline at end of file
diff --git a/src/my_project/interviews/top_150_questions_round_22/ex_78_lowest_common_ancestor_of_binary_tree.py b/src/my_project/interviews/top_150_questions_round_22/ex_78_lowest_common_ancestor_of_binary_tree.py
new file mode 100644
index 00000000..82a7fd31
--- /dev/null
+++ b/src/my_project/interviews/top_150_questions_round_22/ex_78_lowest_common_ancestor_of_binary_tree.py
@@ -0,0 +1,29 @@
+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 lowestCommonAncestor(self, root:TreeNode, p, q):
+        """
+        :type root: TreeNode
+        :type p: TreeNode
+        :type q: TreeNode
+        :rtype: TreeNode
+        """
+
+        if not root: 
+            return 
+        elif root.val == p.val or root.val == q.val: 
+            return root
+        
+        l = self.lowestCommonAncestor(root.left,p,q)
+        r = self.lowestCommonAncestor(root.right,p,q)
+        if l and r:
+            return root 
+        else: 
+            return l or r 
\ No newline at end of file
diff --git a/src/my_project/interviews_typescript/top_150_questions_round_1/test_78_lowest_common_ancestor_of_binary_tree_round_22.ts b/src/my_project/interviews_typescript/top_150_questions_round_1/test_78_lowest_common_ancestor_of_binary_tree_round_22.ts
new file mode 100644
index 00000000..858a96c9
--- /dev/null
+++ b/src/my_project/interviews_typescript/top_150_questions_round_1/test_78_lowest_common_ancestor_of_binary_tree_round_22.ts
@@ -0,0 +1,16 @@
+import { TreeNode } from './TreeNode';      
+
+function lowestCommonAncestor(root: TreeNode | null, p: TreeNode | null, q: TreeNode | null): TreeNode | null {
+    if (root === null || root === p || root === q) {
+        return root;
+    }
+    
+    const left = lowestCommonAncestor(root.left, p, q);
+    const right = lowestCommonAncestor(root.right, p, q);
+    
+    if (left !== null && right !== null) {
+        return root;
+    }
+    
+    return left !== null ? left : right;
+}
\ No newline at end of file
diff --git a/tests/test_150_questions_round_22/test_78_lowest_common_ancestor_of_binary_tree_round_22.py b/tests/test_150_questions_round_22/test_78_lowest_common_ancestor_of_binary_tree_round_22.py
new file mode 100644
index 00000000..6650480d
--- /dev/null
+++ b/tests/test_150_questions_round_22/test_78_lowest_common_ancestor_of_binary_tree_round_22.py
@@ -0,0 +1,71 @@
+import unittest
+from typing import Optional, List
+from src.my_project.interviews.top_150_questions_round_22\
+.ex_78_lowest_common_ancestor_of_binary_tree import Solution, TreeNode
+
+
+class LowestCommonAncestorBinaryTreeTestCase(unittest.TestCase):
+
+    def build_tree(self, values: List[Optional[int]]) -> Optional[TreeNode]:
+        """Build a binary tree from level-order array representation."""
+        if not values or values[0] is None:
+            return None
+        
+        root = TreeNode(values[0])
+        queue = [root]
+        i = 1
+        
+        while queue and i < len(values):
+            node = queue.pop(0)
+            
+            # Left child
+            if i < len(values) and values[i] is not None:
+                node.left = TreeNode(values[i])
+                queue.append(node.left)
+            i += 1
+            
+            # Right child
+            if i < len(values) and values[i] is not None:
+                node.right = TreeNode(values[i])
+                queue.append(node.right)
+            i += 1
+        
+        return root
+    
+    def find_node(self, root: Optional[TreeNode], val: int) -> Optional[TreeNode]:
+        """Find a node with given value in the tree."""
+        if not root:
+            return None
+        if root.val == val:
+            return root
+        left = self.find_node(root.left, val)
+        if left:
+            return left
+        return self.find_node(root.right, val)
+
+    def test_example_1(self):
+        """Test case: LCA of nodes 5 and 1 is 3."""
+        solution = Solution()
+        tree = self.build_tree([3, 5, 1, 6, 2, 0, 8, None, None, 7, 4])
+        p = self.find_node(tree, 5)
+        q = self.find_node(tree, 1)
+        output = solution.lowestCommonAncestor(root=tree, p=p, q=q)
+        self.assertEqual(3, output.val)
+
+    def test_example_2(self):
+        """Test case: LCA of nodes 5 and 4 is 5 (node can be ancestor of itself)."""
+        solution = Solution()
+        tree = self.build_tree([3, 5, 1, 6, 2, 0, 8, None, None, 7, 4])
+        p = self.find_node(tree, 5)
+        q = self.find_node(tree, 4)
+        output = solution.lowestCommonAncestor(root=tree, p=p, q=q)
+        self.assertEqual(5, output.val)
+
+    def test_example_3(self):
+        """Test case: LCA of nodes 1 and 2 is 1."""
+        solution = Solution()
+        tree = self.build_tree([1, 2])
+        p = self.find_node(tree, 1)
+        q = self.find_node(tree, 2)
+        output = solution.lowestCommonAncestor(root=tree, p=p, q=q)
+        self.assertEqual(1, output.val)
\ No newline at end of file