diff --git a/src/my_project/interviews/amazon_high_frequency_23/round_5/longest_common_subsequence.py b/src/my_project/interviews/amazon_high_frequency_23/round_5/longest_common_subsequence.py
new file mode 100644
index 00000000..d5d4d0af
--- /dev/null
+++ b/src/my_project/interviews/amazon_high_frequency_23/round_5/longest_common_subsequence.py
@@ -0,0 +1,22 @@
+from typing import List, Union, Collection, Mapping, Optional
+
+class Solution:
+    def longestCommonSubsequence(self, text1: str, text2: str) -> int:
+
+        # Make a grid of 0's with len(text2) + 1 columns 
+        # and len(text1) + 1 rows.
+        len_1 = len(text1)
+        len_2 = len(text2)
+        dp_grid = [[0]*(len_2+1) for _ in range(len_1+1)]
+
+        # Iterate up each column, starting from the last one. 
+        for j in reversed(range(len_2)):
+            for i in reversed(range(len_1)):
+                if text1[i] == text2[j]:
+                    dp_grid[i][j] = dp_grid[i+1][j+1] + 1
+                else:
+                    dp_grid[i][j] = max(dp_grid[i+1][j], dp_grid[i][j+1])
+
+        # The original problem's answer is in dp_grid[0][0]. Return it.  
+        return dp_grid[0][0]
+
diff --git a/src/my_project/interviews/amazon_high_frequency_23/round_5/lowest_common_ancestor_binary_tree_iv.py b/src/my_project/interviews/amazon_high_frequency_23/round_5/lowest_common_ancestor_binary_tree_iv.py
new file mode 100644
index 00000000..71d4191d
--- /dev/null
+++ b/src/my_project/interviews/amazon_high_frequency_23/round_5/lowest_common_ancestor_binary_tree_iv.py
@@ -0,0 +1,29 @@
+from typing import List, Union, Collection, Mapping, Optional
+
+# Definition for a binary tree node.
+class TreeNode:
+    def __init__(self, x):
+        self.val = x
+        self.left = None
+        self.right = None
+
+class Solution:
+    def lowestCommonAncestor(self, root: TreeNode, nodes: List[TreeNode]) -> 'TreeNode':
+
+        node_set = set(nodes)
+
+        def dfs(node: TreeNode):
+
+            if not node or node in node_set:
+                return node 
+            
+            left = dfs(node.left)
+            right = dfs(node.right)
+
+            if left and right:
+                return node
+            
+            return left if left else right
+        
+        return dfs(root)
+        
\ No newline at end of file
diff --git a/src/my_project/interviews/top_150_questions_round_22/best_time_to_sell_stocks_i.py b/src/my_project/interviews/top_150_questions_round_22/best_time_to_sell_stocks_i.py
new file mode 100644
index 00000000..c863b07d
--- /dev/null
+++ b/src/my_project/interviews/top_150_questions_round_22/best_time_to_sell_stocks_i.py
@@ -0,0 +1,19 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC
+import math
+
+class Solution:
+    def maxProfit(self, prices: List[int]) -> int:
+
+        min_price = math.inf
+        max_profit = 0
+        len_prices = len(prices)
+
+        for i in range(len_prices):
+
+            if prices[i] < min_price:
+                min_price = prices[i]
+            elif prices[i] - min_price > max_profit:
+                max_profit = prices[i] - min_price
+
+        return max_profit
\ No newline at end of file
diff --git a/src/my_project/interviews/top_150_questions_round_22/best_time_to_sell_stocks_ii.py b/src/my_project/interviews/top_150_questions_round_22/best_time_to_sell_stocks_ii.py
new file mode 100644
index 00000000..0de5446b
--- /dev/null
+++ b/src/my_project/interviews/top_150_questions_round_22/best_time_to_sell_stocks_ii.py
@@ -0,0 +1,25 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC
+
+class Solution:
+    def maxProfit(self, prices: List[int]) -> int:
+
+        i = 0
+        peak = None
+        valley = None
+        len_prices = len(prices)
+        result = 0 
+
+        while i < len(prices) - 1:
+
+            while i < len_prices - 1 and prices[i] >= prices[i+1]:
+                i += 1
+            valley = prices[i]
+
+            while i < len_prices - 1 and prices[i] <= prices[i+1]:
+                i += 1
+            peak = prices[i]
+
+            result += peak - valley
+        
+        return result
diff --git a/tests/test_150_questions_round_22/test_best_time_to_sell_stocks_i_round_22.py b/tests/test_150_questions_round_22/test_best_time_to_sell_stocks_i_round_22.py
new file mode 100644
index 00000000..7f97e98a
--- /dev/null
+++ b/tests/test_150_questions_round_22/test_best_time_to_sell_stocks_i_round_22.py
@@ -0,0 +1,11 @@
+import unittest
+from src.my_project.interviews.top_150_questions_round_22\
+.best_time_to_sell_stocks_i import Solution
+
+class BestTimeToSellStockTestCase(unittest.TestCase):
+
+    def test_best_time_to_sell_stock(self):
+        solution = Solution()
+        output = solution.maxProfit(prices=[7,1,5,3,6,4])
+        target = 5 
+        self.assertEqual(output, target)
\ No newline at end of file
diff --git a/tests/test_150_questions_round_22/test_best_time_to_sell_stocks_ii_round_22.py b/tests/test_150_questions_round_22/test_best_time_to_sell_stocks_ii_round_22.py
new file mode 100644
index 00000000..d1370fb1
--- /dev/null
+++ b/tests/test_150_questions_round_22/test_best_time_to_sell_stocks_ii_round_22.py
@@ -0,0 +1,13 @@
+import unittest
+import unittest
+from src.my_project.interviews.top_150_questions_round_22\
+.best_time_to_sell_stocks_ii import Solution
+
+
+class BestTimeToSellStockTestCase(unittest.TestCase):
+
+    def test_best_time_to_sell_stock(self):
+        solution = Solution()
+        output = solution.maxProfit(prices=[7,1,5,3,6,4])
+        target = 7 
+        self.assertEqual(output, target)
\ No newline at end of file