contains-duplicate solution

Author: toychip

contains-duplicate/toychip.java

@@ -0,0 +1,16 @@
+import java.util.HashSet;
+import java.util.Set;
+
+class Solution {
+    public boolean containsDuplicate(int[] nums) {
+        Set<Integer> answer = new HashSet<>();
+        for (int num : nums) {
+            if (!answer.contains(num)) {
+                answer.add(num);
+            } else {
+                return true;
+            }
+        }
+        return false;
+    }
+}