diff --git a/src/my_project/interviews/amazon_high_frequency_23/common_algos/two_sum_round_4.py b/src/my_project/interviews/amazon_high_frequency_23/common_algos/two_sum_round_4.py
new file mode 100644
index 00000000..c04ad7c7
--- /dev/null
+++ b/src/my_project/interviews/amazon_high_frequency_23/common_algos/two_sum_round_4.py
@@ -0,0 +1,20 @@
+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_4.py b/src/my_project/interviews/amazon_high_frequency_23/common_algos/valid_palindrome_round_4.py
new file mode 100644
index 00000000..013e283c
--- /dev/null
+++ b/src/my_project/interviews/amazon_high_frequency_23/common_algos/valid_palindrome_round_4.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 characters
+        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
diff --git a/src/my_project/interviews/amazon_high_frequency_23/round_6/minimum_number_of_operations_to_turn_array_into_a_palindrom.py b/src/my_project/interviews/amazon_high_frequency_23/round_6/minimum_number_of_operations_to_turn_array_into_a_palindrom.py
new file mode 100644
index 00000000..e695ccce
--- /dev/null
+++ b/src/my_project/interviews/amazon_high_frequency_23/round_6/minimum_number_of_operations_to_turn_array_into_a_palindrom.py
@@ -0,0 +1,31 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC, abstractmethod
+
+class Solution:
+    def minimumOperations(self, nums: List[int]) -> int:
+
+        l, r = 0, len(nums) - 1
+        ls = nums[l]
+        rs = nums[r]
+        answer = 0
+
+        while l < r: 
+
+            if ls == rs: 
+                l += 1
+                r -= 1
+                ls = nums[l]
+                rs = nums[r]                
+            elif ls < rs: 
+                l += 1
+                ls += nums[l]
+                answer += 1
+            else: 
+                r -= 1
+                rs += nums[r]
+                answer += 1
+
+        return answer
+
+
+