CS 1501
Lempel-Ziv Welch Decoding

Trace of table insertions and output strings for the decoding
of the encoded file produced by the handout lzw.txt.  Note that
in this case, even though the dictionary will contain the same 
data, it will this time be accessed using the code as the key
value (whereas in the encoding the string was the key value).  Also
note that the new (string, code) pairs are added to the dictionary
a step later than they were in encoding.  This can be a problem in
some cases (as we will discuss).

Initially: insert codes 0..255 into the dictionary for each possible
           8-bit sequence.  For strings, this amounts to the values
           in the extended ASCII sequence.

STEP    INPUT CODE      OUTPUT STRING     ADD to Dictionary (CODE #)
----    ----------      -------------     --------------------------
1     83 (ASCII('S'))       'S'                     ---
2     69 (ASCII('E'))       'E'                 'SE' (256)
3     69 (ASCII('E'))       'E'                 'EE' (257)
4     32 (ASCII(' '))       ' '                 'E ' (258)
5     83 (ASCII('S'))       'S'                 ' S' (259)
6     80 (ASCII('P'))       'P'                 'SP' (260)
7     79 (ASCII('O'))       'O'                 'PO' (261)
8     84 (ASCII('T'))       'T'                 'OT' (262)
9     32 (ASCII(' '))       ' '                 'T ' (263)
10    82 (ASCII('R'))       'R'                 ' R' (264)
11    85 (ASCII('U'))       'U'                 'RU' (265)
12    78 (ASCII('N'))       'N'                 'UN' (266)
13    46 (ASCII('.'))       '.'                 'N.' (267)
14         264              ' R'                '. ' (268)
15         266              'UN'                ' RU' (269)
16         259              ' S'                'UN ' (270)
17         261              'PO'                ' SP' (271)
18         263              'T '                'POT' (272)
19         265              'RU'                'T R' (273)
20         267              'N.'                'RUN' (274)
21         269              ' RU'               'N. ' (275)
22    78 (ASCII('N'))       'N'                 ' RUN' (276)
23         276              ' RUN'              'N ' (277)
24         271              ' SP'               ' RUN ' (278)
25         262              'OT'                ' SPO' (279)
26         268              '. '                'OT.' (280)
27         274              'RUN'               '. R' (281)
28         278              ' RUN '             'RUN ' (282)
29         274              'RUN'               ' RUN R' (283)
30    46 (ASCII('.'))       '.'                      ---