diff --git a/combination-sum/sangbeenmoon.py b/combination-sum/sangbeenmoon.py
new file mode 100644
index 0000000000..998009875f
--- /dev/null
+++ b/combination-sum/sangbeenmoon.py
@@ -0,0 +1,26 @@
+# TC : O(2^target) 재귀 트리의 분기 수
+# SC : O(target/min(candidates)) 재귀 스택 깊이
+
+class Solution: 
+    def combinationSum(self, candidates: List[int], target: int) -> List[List[int]]:
+        self.answer = []
+        for i in range(len(candidates)):
+            self.go(i, candidates, [candidates[i]], candidates[i], target)
+
+        return self.answer
+
+    def go(self, i:int, candidates: List[int], nums: List[int], sum_: int, target: int):
+        if sum_ == target:
+            self.answer.append(nums.copy())
+
+        for j in range(i, len(candidates)):
+            if candidates[j] + sum_ <= target:
+                nums.append(candidates[j])
+                self.go(j, candidates, nums, sum_ + candidates[j], target)
+                nums.pop()
+
+        
+
+
+            
+
diff --git a/number-of-1-bits/sangbeenmoon.py b/number-of-1-bits/sangbeenmoon.py
new file mode 100644
index 0000000000..144e437598
--- /dev/null
+++ b/number-of-1-bits/sangbeenmoon.py
@@ -0,0 +1,9 @@
+class Solution:
+    def hammingWeight(self, n: int) -> int:
+        cnt = 0
+        while n > 0:
+            if n % 2 == 1:
+                cnt = cnt + 1
+            n = n // 2
+            print(n)
+        return cnt
diff --git a/valid-palindrome/sangbeenmoon.py b/valid-palindrome/sangbeenmoon.py
new file mode 100644
index 0000000000..90967855cb
--- /dev/null
+++ b/valid-palindrome/sangbeenmoon.py
@@ -0,0 +1,21 @@
+# TC : O(n) 
+# SC : O(n)
+
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+        refined_s = []
+
+        for ch in s:
+            if 'a' <= ch and ch <= 'z' or ('0' <= ch and ch <= '9'):
+                refined_s.append(ch)
+                continue
+
+            if 'A' <= ch and ch <= 'Z':
+                refined_s.append(ch.lower())
+        
+        for i in range(len(refined_s)):
+            j = len(refined_s) - i - 1
+            if refined_s[i] != refined_s[j]:
+                return False
+            
+        return True