PA2: LZ78/LZW Data Compression at University of Michigan - Prof. Sugih Jamin, Exams of Algorithms and Programming

Download PA2: LZ78/LZW Data Compression at University of Michigan - Prof. Sugih Jamin and more Exams Algorithms and Programming in PDF only on Docsity! Discussion: No The Universi vember 7, 2007 ty of Michigan 1 Agenda Questions on anything Quick Huffman Review PA2: LZ78/LZW Specific questions : 2 PA2: LZ78/LZW Encoding Encoding process − Quick review of exam question : 5 PA2: LZ78/LZW Encoding Okay, so we know how to create cod Trie − Putting into trie (Initial size: 256 − Start with 9-bit symbols (256-51 f− Increase size i necessary − When you move from 9-bit to 10 code (char* is NULL). This implie b lsym o s − Perhaps, an n-ary trie would be : es. How do we store them? = 0-255) 1) -bit symbols, don’t use 511 for any s that you are now moving to 10-bit useful here. 6 PA2: LZ78/LZW Encoding Magic Cookie: 16-bits LZW: 0010 Original Sym Size: 8-bits (If ASCII, l S S * h b lInitia ym ize : It is t e sym o s string=256 , then initial sym size = − Size will increase dynamically − Use trie to do the encoding − Reserve 2^k-1 symbol for transi : then 8-bits) h ( f f dize you start wit I your irst co e 9) tion to next symbol size 7 PA2: LZ78/LZW Encoding Visit this website for issues regardin strings htt // k l /1989/10/0p: mar ne son.us - Strings are stored in a reve Retrieve characters and sto- them to get the string : g use of stack for getting the decoded 1/l d t i /zw- a a-compress on rse order in our string buffer re them in our stack buffer and pop 10 Questions? Any questions? $8 » DATA STRUCTURES " AND ALGORITHMS 11