diff --git a/contains-duplicate/ljh981009.ts b/contains-duplicate/ljh981009.ts
new file mode 100644
index 0000000000..b729ab9396
--- /dev/null
+++ b/contains-duplicate/ljh981009.ts
@@ -0,0 +1,4 @@
+function containsDuplicate(nums: number[]): boolean {
+  const result = new Set(nums);
+  return result.size !== nums.length;
+}