E0113chars z000011000 howtomakeshortestcodesfor

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Unformatted text preview: ariable length code Prefix Codes Prefix Codes Build a “decision tree”, characters at leaves EXAMPLES: Use to encode example: U = 10010 Use to decode example: 0101 = S Prefix Codes Prefix Codes IDEA: frequent letters should have SHORTEST codes, so overall space used is minimized. E = 011 (3 chars) Z = 000011000 How to make shortest codes for How to make shortest codes for most frequent letters David Huffman discovered the method: a term paper while a graduate student at MIT. ANIMATION: http://www.beluga.ch/code/apple Example Example AEDAECDEAEEBDCEEDBCDEEDAEBEB CCE Compute the frequencies of each letter: – A: 4 – B: 4 – C: 5 – D: 6 – E: 12 Example Example Letter Frequency A 4 B 4 C 5 D We build the tree from the bottom up. 6 E 12 Start with singleton vertices, labeled with their frequencies A B C D E 4 4 5 6 12 Find the two smallest frequencies, and combine t...
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This document was uploaded on 04/02/2014.

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