6 [5 Points] Consider a doubly linked circular list as shown, with the first node pointed to by first. Write the statements to add a new node pointed to by newptr, before the first node in the list. (Give only the essential statements, not a whole function) CMSC3621: Data Structures (Spring 2021) prev prev prev 0 first data data data next next next 7 [5 Points] Give the Preorder, Inorder, and Postorder traversals of the following binary trees. A B E F H