I've put out the asn05soln.c code on the web page.
One of you asked if it was easy to see a picture of the binary tree
so I did a quick hack that at least will give you a view with indentation
that lets you see the structure but with out the actual lines drawn.
You can get it from my asn05soln.c and can probably tweek it a little
more to draw the lines.  Here's some of the out put for Voyage of the Beagle.
Notice that the words are in alphabetical order from top to bottom and that
the first word, project, which is first in the VOB text, is the root of the
tree and shows up at the extreme left halfway down.  Thats the extent of
my 5 min attention span before heading home.


time r_tree_search computer search of vbgle for whales < vb*txt
                                   000 23
                            1 51
                                   are 1184
                     beagle 89
                                   before 203
                            by 1635
                                   darwin 7
              etext 32
                                   file 6
                            files 7
                                   final 5
                     for 1111
                                   forth 24
                            free 28
                                   get 31
       gutenberg 22
                                   header 1
                            important 15
                                   impression 8
                     in 4295
                                   information 16
                            laws 17
                                   look 44
              of 9465
                                   official 3
                            on 1877
                                   open 93
                     our 359
                                   outline 19
                            over 244
                                   posting 1
project 37
                                   projected 8
                            proofread 2
                                   reach 26
                     readable 3
                            reader 2
              readers 3
                                   reading 4
                            release 4
                                   remedies 3
                     remove 8
                                   request 6
                            require 11
                                   return 49
       s 397
                                   scanned 2
                            separate 37
                                   september 28
                     series 6
                                   since 82
                            sure 32
                                   take 71
              the 16930
                                   these 769
                            to 4135
                                   vanilla 1
                     voyage 75
                                   we 1173
                            world 69
                                   your 30