feat: contains duplicate

Author: minji-go

contains-duplicate/minji-go.java

@@ -0,0 +1,17 @@
+import java.util.HashSet;
+import java.util.Set;
+
+class Solution {
+    public boolean containsDuplicate(int[] nums) {
+        Set<Integer> count = new HashSet<>();
+        boolean answer = false;
+        for(int num : nums){
+            if(count.contains(num)) {
+                answer = true;
+                break;
+            }
+            count.add(num);
+        }
+        return answer;
+    }
+}