diff --git a/contains-duplicate/jiunshinn.py b/contains-duplicate/jiunshinn.py
new file mode 100644
index 000000000..44fab4ad8
--- /dev/null
+++ b/contains-duplicate/jiunshinn.py
@@ -0,0 +1,30 @@
+# 시간 복잡도 : o(n)
+# 공간 복잡도 o(n)
+
+
+class Solution:
+    def containsDuplicate(self, nums: List[int]) -> bool:
+        hashmap = {}
+
+        for i, n in enumerate(nums):
+            if n in hashmap:
+                return True
+            hashmap[n] = i
+        return False
+
+
+# -------------------------------------------------------------------------------------------------------- #
+
+# 시간 복잡도 : o(n)
+# 공간 복잡도 o(n)
+
+
+class Solution:
+    def containsDuplicate(self, nums: List[int]) -> bool:
+        seen = set()
+
+        for n in nums:
+            if n in seen:
+                return True
+            seen.add(n)
+        return False
diff --git a/two-sum/jiunshinn.py b/two-sum/jiunshinn.py
new file mode 100644
index 000000000..73827b846
--- /dev/null
+++ b/two-sum/jiunshinn.py
@@ -0,0 +1,12 @@
+# time complexity : o(n)
+# space complexity : o(n)
+class Solution:
+    def twoSum(self, nums: List[int], target: int) -> List[int]:
+        hashmap = {}
+
+        for i, n in enumerate(nums):
+            diff = target - n
+            if diff in hashmap:
+                return [i, hashmap[diff]]
+            else:
+                hashmap[n] = i