diff --git a/contains-duplicate/grapefruit13.ts b/contains-duplicate/grapefruit13.ts
new file mode 100644
index 0000000000..c98219cbf3
--- /dev/null
+++ b/contains-duplicate/grapefruit13.ts
@@ -0,0 +1,16 @@
+/**
+ * @description nums 배열에서 중복 숫자 확인
+ * @param nums - 숫자 배열
+ * @returns boolean - 중복 숫자 여부
+ */
+const containsDuplicate = (nums: number[]) => {
+  const hasSeen = new Set<number>();
+
+  for (const num of nums) {
+    if (hasSeen.has(num)) {
+      return true;
+    }
+    hasSeen.add(num);
+  }
+  return false;
+};
diff --git a/two-sum/grapefruit13.ts b/two-sum/grapefruit13.ts
new file mode 100644
index 0000000000..42ca5315b8
--- /dev/null
+++ b/two-sum/grapefruit13.ts
@@ -0,0 +1,18 @@
+/**
+ * @description nums 배열에서 두 수를 더해 target을 만족하는 인덱스를 반환
+ * @param {number[]} nums - 숫자 배열
+ * @param {number} target - 목표 숫자
+ * @return {number[]} - 두 수의 인덱스
+ */
+var twoSum = function (nums, target) {
+  const map = new Map();
+
+  for (let i = 0; i < nums.length; i++) {
+    const current = nums[i];
+    const needed = target - current;
+    if (map.has(needed)) {
+      return [map.get(needed), i];
+    }
+    map.set(current, i);
+  }
+};