Question

Which of the following is the greedy choice in solving the Huffman code problem? A. Lowest frequency of character(s) B. Highest frequency of character(s) Lowest rank of character(s) in alphabet set (e.g., character a's rank is 1, b's rank is 2.) D. Highest frequency of character(s).

Answer 1

A. Lowest frequency of characters

Huffman code is a data compression algorithm which uses the greedy technique for its implementation. The algorithm is based on the frequency of the characters appearing in a file. The characters with lowest frequest are chosen and linked together as children of a common parent symbol. This method is repeated till a huffman tree is generated. Refer the image below to understand how the tree is created.

(a) f:5 e:9 c:12 b:13 d:16 a:45 (b) c:12 b:13 14 d:16) a:45 0 1 f:5 e:9 14 d:16 (25 a:45 (d) 25 (30 a:45 0. 0 c:12 b:13 0 1 c:12 b:13 f:5 e:9 0 1 (14) d:16 0 1 f:5 e:9 (e) a:45 (55) (f) (100) 1 0 25 30 a:45 55 0 14) d:16 25 (30 0 c:12 b:13 0 f:5 0 0 14) e:9 c:12 b:13 d:16 0 f:5 e:9

In the image above we get a path for each character. The low the frequency of that character, longer is the path/code for it. For eg: a has the highest frequency so the smallest code.

a = 0

b = 101

c = 100

d = 111

e = 1101

f = 1100