adding the ptrs implementation of iterator incrementing

lectures/19_trees_II/ds_set_main.cpp

@@ -8,8 +8,11 @@ int main() {
     // insert some values into the set
     numbers.insert(10);
     numbers.insert(5);
+    numbers.insert(88);
     numbers.insert(20);
+    numbers.insert(49);
     numbers.insert(15);
+    numbers.insert(36);
     numbers.insert(5); // Duplicate value (won't be inserted)
 
     // print the elements of the set
@@ -27,5 +30,13 @@ int main() {
         std::cout << value << " is not found in the set." << std::endl;
     }
 
+    // check if a specific value exists in the set
+    value = 66;
+    if (numbers.find(value) != numbers.end()) {
+        std::cout << value << " is found in the set." << std::endl;
+    } else {
+        std::cout << value << " is not found in the set." << std::endl;
+    }
+
     return 0;
 }