contains duplicate solution

Author: eunhwa99

contains-duplicate/eunhwa99.java

@@ -0,0 +1,14 @@
+class Solution {
+    public boolean containsDuplicate(int[] nums) {
+         HashSet<Integer> seen = new HashSet<>();
+        for (int num : nums) {
+            if (!seen.add(num)) {
+                return true;
+            }
+        }
+        
+        return false;
+
+        
+    }
+}