diff --git a/contains-duplicate/yeongu.cpp b/contains-duplicate/yeongu.cpp
new file mode 100644
index 000000000..2afd5659b
--- /dev/null
+++ b/contains-duplicate/yeongu.cpp
@@ -0,0 +1,13 @@
+class Solution {
+public:
+    bool containsDuplicate(vector<int>& nums) {
+        set<int> unique;
+        for (int i : nums) {
+            if (unique.find(i) != unique.end()) {
+                return true;
+            }
+            unique.insert(i);
+        }
+        return false;
+    }
+};
diff --git a/number-of-1-bits/yeongu.cpp b/number-of-1-bits/yeongu.cpp
new file mode 100644
index 000000000..1951308b7
--- /dev/null
+++ b/number-of-1-bits/yeongu.cpp
@@ -0,0 +1,12 @@
+class Solution {
+public:
+    int hammingWeight(int n) {
+        int cnt = 0;
+        while(n>0){
+            int val = n%2;
+            cnt+=val;
+            n/=2;
+        }
+        return cnt;
+    }
+};