c++英文试题 Suppose that a program has declared these three vari

c++英文试题
Suppose that a program has declared these three variables using the dnode class shown
above.
dnode *b;
dnode *h;
dnode *z;
After executing part of the program,the pointer b is a head pointer for a non-empty
linked list.
Write some code that can be placed in the program at this point to make a complete copy
of b's linked list.At the end of your code,b should be unchanged,h should be the head
pointer of the new list,and z should be the tail pointer of the new list.If necessary,you
may declare other dnode * variables to use in your algorithm.