用霍夫曼编码的方式实现对一个文本文件的编码和解码。本程序产生的编码后的文件应该尽可能的小，解码后的文件应该和原来的文件是一样的。本算法的实现应该是高效的。

一些可能用到的数据结构和方法在下面列出。如果你发现另外一种更好的数据结或者方法，这很好，你并不需要用到任何特定的数据结构。

-Huffman encoding of the way to encode and decode a text file. This procedure produced encoded files should be as small as possible, the file should be decoded and the original file is the same. The implementation of this algorithm is efficient.

Some data structure and methods may be used are listed below. If you find another better data node or method, which is good, you do not need to use any particular data structure.