diff --git a/contains-duplicate/nayeongdev.js b/contains-duplicate/nayeongdev.js
new file mode 100644
index 0000000000..9f9f974c73
--- /dev/null
+++ b/contains-duplicate/nayeongdev.js
@@ -0,0 +1,14 @@
+/**
+ * @param {number[]} nums
+ * @return {boolean}
+ * O(nlog(n)) : 정렬 O(nlog(n)) + 탐색 O(n)
+ */
+var containsDuplicate = function (nums) {
+    const sortedNums = nums.toSorted((a, b) => a - b)
+    for (let i = 0; i < nums.length - 1; i++) {
+        if (sortedNums[i] === sortedNums[i + 1]) {
+            return true
+        }
+    }
+    return false
+};
diff --git a/two-sum/nayeongdev.js b/two-sum/nayeongdev.js
new file mode 100644
index 0000000000..90f498c950
--- /dev/null
+++ b/two-sum/nayeongdev.js
@@ -0,0 +1,18 @@
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number[]}
+ */
+var twoSum = function (nums, target) {
+    for (let i = 0; i < nums.length; i++) {
+        for (let j = i + 1; j < nums.length; j++) {
+            if (nums[i] + nums[j] === target) {
+                return [i, j];
+            }
+            if (nums[i] + nums[j] > target) {
+                continue;
+            }
+        }
+    }
+    return [];
+};