diff --git a/combination-sum/mandel-17.py b/combination-sum/mandel-17.py
new file mode 100644
index 0000000000..7fd2261635
--- /dev/null
+++ b/combination-sum/mandel-17.py
@@ -0,0 +1,19 @@
+from typing import List
+
+class Solution:
+    def combinationSum(self, candidates: List[int], target: int) -> List[List[int]]:
+        result = []
+        
+        def dfs(csum, index, path):
+            if csum < 0:
+                return
+            if csum == 0:
+                result.append(path)
+                return
+        
+            for i in range(index, len(candidates)):
+                dfs(csum - candidates[i], i, path + [candidates[i]])
+            
+        dfs(target, 0, [])
+        return result
+        
diff --git a/number-of-1-bits/mandel-17.py b/number-of-1-bits/mandel-17.py
new file mode 100644
index 0000000000..2430138e22
--- /dev/null
+++ b/number-of-1-bits/mandel-17.py
@@ -0,0 +1,10 @@
+import collections
+
+class Solution:
+    def hammingWeight(self, n: int) -> int:
+        two_digit = []
+        while n >= 1:
+            two_digit.append(n % 2)
+            n = n // 2
+        cnt_dict = collections.Counter(two_digit)
+        return cnt_dict[1]
diff --git a/valid-palindrome/mandel-17.py b/valid-palindrome/mandel-17.py
new file mode 100644
index 0000000000..cf9eb0fdd3
--- /dev/null
+++ b/valid-palindrome/mandel-17.py
@@ -0,0 +1,4 @@
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+        ch = [c.lower() for c in s if c.isalnum()]
+        return ch == ch[::-1]