add set question

18_Hashing/HashSet/prb1.java

@@ -0,0 +1,14 @@
+import java.util.*;
+
+public class prb1 {
+    public static void main(String[] args) {
+        int arr[] = {4,3,2,5,6,7,3,4,2,1};
+        HashSet<Integer> set = new HashSet<>();
+
+        for(int i = 0;i<arr.length ;i++){
+            set.add(arr[i]);
+        }
+        System.out.println("ans = " + set.size());
+        //its take 0(n) time complexity..
+    }
+}

18_Hashing/HashSet/tree.java

@@ -0,0 +1,19 @@
+import java.util.*;
+
+public class tree {
+    public static void main(String[] args) {
+        TreeSet<String> ts = new TreeSet<>();
+        ts.add("bottle");
+        ts.add("phone");
+        ts.add("sope");
+        ts.add("apple");
+        ts.add("mac");
+
+        for(String obj : ts){
+            System.out.println(obj);
+            //The output is printing in sorted order..
+        }
+
+
+    }
+}