利用二叉树结构实现赫夫曼编/解码器。

基本要求：

1、　　初始化(Init)：能够对输入的任意长度的字符串s进行统计，统计每个字符的频度，并建立赫夫曼树

2、　　建立编码表(CreateTable)：利用已经建好的赫夫曼树进行编码，并将每个字符的编码输出。

3、　　编码(Encoding)：根据编码表对输入的字符串进行编码，并将编码后的字符串输出。

4、　　译码(Decoding)：利用已经建好的赫夫曼树对编码后的字符串进行译码，并输出译码结果。

5、　　打印(Print)：以直观的方式打印赫夫曼树（选作）

6、　　计算输入的字符串编码前和编码后的长度，并进行分析，讨论赫夫曼编码的压缩效果。

-Binary tree structure to achieve a Huffman encoder/decoder. Basic requirements: 1, initialize the Init: any length of the input string s statistics, statistical frequency of each character, and the establishment of the Huffman tree, to the establishment of the coding table (the CreateTable): use of already built the Huffman tree is encoded, and each character encoding output. 3, the encoding (Encoding): According to the coding table of the input string is encoded, and encoded string output. Decoding (Decoding): the use of the Huffman tree has been built to decode the encoded string, and outputs the decoding results. 5, print (the Print): an intuitive way to print the Huffman tree (option for) 6 to calculate the length of the string encoding of the input pre-encoded, and analyzed, to discuss the Huffman encoding compression.