src/solution/Solution.java

@@ -148,8 +148,4 @@ public class Solution {
         }
         return strs[0];
     }
-
-    public static ListNode mergeTwoLists(ListNode list1, ListNode list2) {
-
-    }
 }

src/solution/test.java

@@ -21,7 +21,10 @@ public class test {
 //        System.out.println(result);
 //        int m = Solution.majorityElement(nums1);
 //        System.out.println(m);
-
+        HashMap<Integer,Integer> map = new HashMap<>();
+        HashSet<Integer> set1 = new HashSet<>();
+        new LinkedHashSet<>();
+        new TreeSet<>();
     }
 
 }