contains-duplicate solution

Author: chjung99

contains-duplicate/chjung99.java

@@ -0,0 +1,20 @@
+/**
+ * time: O(n)
+ * space: O(n)
+ */
+
+import java.util.*;
+
+class Solution {
+    public boolean containsDuplicate(int[] nums) {
+        Set<Integer> hash = new HashSet<>();
+
+        for (int num: nums){
+            if (hash.contains(num)) return true;
+            hash.add(num);
+        }
+
+        return false;
+    }
+}
+