Huffmankoodausmenetelmiä

Huffman coding is a lossless data compression algorithm. It was developed by David A. Huffman in 1952. The algorithm works by assigning shorter codes to more frequent symbols and longer codes to less frequent symbols. This is achieved by building a binary tree where each leaf node represents a symbol and its frequency. The path from the root to a leaf node determines the code for that symbol, with a left branch typically representing a '0' and a right branch a '1'.

To construct the Huffman tree, all symbols are initially treated as individual nodes with their respective frequencies. These nodes are then repeatedly merged into parent nodes, with the two nodes having the lowest frequencies being combined at each step. The frequency of the new parent node is the sum of the frequencies of its children. This process continues until only one node, the root, remains.

Once the tree is built, codes are generated by traversing from the root to each leaf. The resulting binary codes are prefix codes, meaning no code is a prefix of another code. This property is crucial for unambiguous decoding. When decompressing, the encoded bitstream is read, and the decoder traverses the Huffman tree based on the bits encountered. When a leaf node is reached, the corresponding symbol is output, and the process restarts from the root for the next symbol. Huffman coding is widely used in various applications, including text compression, image compression (like in JPEG), and network protocols.