实现哈弗曼编码及其压缩。对一个文本文件中的字符进行哈夫曼编码，生成编码文件（后缀名.cod）；反过来，可将一个编码文件还原为一个文本文件(.txt)。-Encoding and compression to achieve Hafu Man. A text file on the characters in the Huffman code, generate code files (suffix. Cod) in turn, can restore an encoded file as a