diff --git a/contains-duplicate/mandel-17.py b/contains-duplicate/mandel-17.py
new file mode 100644
index 0000000000..4aa2f4a003
--- /dev/null
+++ b/contains-duplicate/mandel-17.py
@@ -0,0 +1,14 @@
+from typing import List
+
+class Solution:
+    def containsDuplicate(self, nums: List[int]) -> bool:
+        stack_list = []
+        for i, n in enumerate(nums[:-1]):
+            stack_list.append(n)
+            if nums[i+1] in stack_list:
+                return True
+            else:
+                if i == len(nums[:-2]):
+                  return False
+                continue
+                
diff --git a/top-k-frequent-elements/mandel-17.py b/top-k-frequent-elements/mandel-17.py
new file mode 100644
index 0000000000..775721df2f
--- /dev/null
+++ b/top-k-frequent-elements/mandel-17.py
@@ -0,0 +1,14 @@
+from typing import List
+
+class Solution:
+    def topKFrequent(self, nums: List[int], k: int) -> List[int]:
+        nums_dict = {}
+        for n in nums:
+          if n not in nums_dict.keys():
+            nums_dict[n] = 1
+          else:
+            nums_dict[n] += 1
+
+        frequent_rank = sorted(nums_dict.items(), key=lambda item:item[1], reverse=True)
+        return [frequent_rank[j][0] for j in range(k)]
+        
diff --git a/two-sum/mandel-17.py b/two-sum/mandel-17.py
new file mode 100644
index 0000000000..029fde1a89
--- /dev/null
+++ b/two-sum/mandel-17.py
@@ -0,0 +1,10 @@
+from typing import List
+
+class Solution:
+    def twoSum(self, nums: List[int], target: int) -> List[int]:
+        for i, v in enumerate(nums):
+            second_value = target - v
+            
+            if second_value in nums[i+1:]:
+                return [i, nums[i+1:].index(second_value) + i+1]
+