How to write Huffman coding algorithm using PHP

How to use PHP to write Huffman coding algorithm

Introduction:
The Huffman coding algorithm is a classic compression algorithm that can perform efficient compression operations on data such as text. In this article, we will learn how to write the Huffman coding algorithm using PHP and give corresponding code examples.

1. Introduction to Huffman Coding Algorithm
The Huffman coding algorithm is a coding algorithm based on a binary tree. It constructs a Huffman tree based on the frequency of the characters to be encoded, and then The shape of the Huffman tree assigns a unique encoding to each character. The higher the frequency of the encoded characters, the shorter the corresponding encoding, thereby achieving the effect of data compression.

2. PHP code to implement Huffman coding
The following is a code example of the Huffman coding algorithm written in PHP:

class HuffmanNode {

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}

//Test code
$text = "hello world!";
$root = buildHuffmanTree($text);
$map = array();
buildCodeMap($root, ' ', $map);
$encodedText = encodeText($text, $map);
$decodedText = decodeText($encodedText, $root);

echo "Original text:" . $ text . "
";
echo "Encoded text:" . $encodedText . "
";
echo "Decoded text:" . $decodedText . "
";
?>

3. Example explanation
We use a simple example to illustrate the use of Huffman coding algorithm. Assuming that the text to be encoded is "hello world!", we will explain step by step the process of code execution.

1. First, we need to create a Huffman coding tree. We use the buildHuffmanTree function to build a Huffman tree, which returns the root node of the tree.
2. Then, we use the buildCodeMap function to establish the character-to-encoding mapping. It recursively traverses the Huffman tree. When a leaf node is traversed, it indicates that the node corresponds to a character, and the character and encoding are added to the mapping relationship.
3. Next, we use the encodeText function to encode the original text. It traverses each character of the original text and converts the characters into the corresponding encoding according to the mapping relationship.
4. Finally, we use the decodeText function to decode the encoding. It starts from the root node and navigates according to each bit of the encoding. When it encounters a leaf node, it means that the encoding of this bit has found the corresponding character and adds the character to the decoding result.

Finally, we print out the original text, encoded text and decoded text to verify the correctness of the algorithm.

Summary:
This article introduces the method of writing Huffman coding algorithm using PHP and gives corresponding code examples. The Huffman coding algorithm is an efficient compression algorithm that can effectively compress text and other data and reduce data storage and transmission overhead. I hope this article can help readers better understand and apply the Huffman coding algorithm.

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