Forgot to allocate the generated numbers in the generator so that they don't repeat

impl_generator.cpp

@@ -13,6 +13,8 @@ int ImplGenerator::get_next_num()
     }
     while (already_generated_numbers.count(num) > 0);
     
+    already_generated_numbers.emplace(num);
+
     internal_counter++;
 
     return num;