Huffman code uses a different number of bits used to encode characters: it uses fewer bits to represent common characters and more bits to represent rare characters. Huffman codes are used for compressing data files. Huffman Code

Binary tree where characters are at leafs. To determine character code you form a binary string by traversing the tree from the root node to a leaf, e.g. a = 000 b = 001 Huffman Tree

Traverse Huffman tree starting from the root until you reach a letter. When you reach a letter print it and start traversing from the root again a b e Decoding Huffman Bit String

1)Count the number of times each character appears in the sentence (character weight) 2)Build a priority queue containing TreeNodes initialized with character and its weight such that lowest weight characters are at the top 3)While the priority queue has more than one element -Pop two elements from the priority queue -Combine them into a binary tree in which the weight of the tree root is the sum of the weights of its children -Insert the newly created tree back into the priority queue Building Huffman Tree

Write a program that: -reads a sentence from cin -Builds a Huffman tree and encodes the sentence into Huffman code string Encode(const string& message, TreeNode *& huffman); -Decodes the Huffman code back into a sentence string Decode(const string& code, const TreeNode *& huffman); Exercise: Huffman Codec

Encode function: -Use the code from the previous lab to count character appearances and build the priority queue -Build Huffman tree by rearranging the priority queue -Write a string HuffmanCode(char letter, const TreeNode *& huffman) function that returns Huffman code of a specified character by walking the Huffman tree -For each character in the sentence call HuffmanCode and concatenate the result. Tips: Huffman Encoder

Read chapter 8, prepare for quiz next class. I will randomly question 10 students. Correct answer earns 1%, incorrect earns -2%.Assignment