Some Problems about Trees

1. How many edges does a tree with 21 nodes have?
   
2. Draw the father code for the tree shown below, in the sense
   of part (c) on page 149 of the text
   
3. Draw the extended Prüfer code for that tree, as described in
   part (d) on page 150.  
4. [Extra Credit]  In the 3rd paragraph on page 152, the authors
   describe the Prüfer code, and how it is obtained from the extended
   Prüfer code discussed on page 150.  And on page 151, they show
   by example how one might obtain the tree from just the Prüfer code.
   What tree is given by this Prüfer code:  4413321