说明：  哈弗曼编码，给出输入文件content.txt，里面包含一段文字，编程实现上面选择的一种编码方法，将输入文件编码后的结果输出到encode.txt；读入上面编码后的结果encode.txt，编程实现解码过程（需要编码时的哈夫曼树，具体数据结构及保存自己设计），将解码后的结果输出到decode.txt；
(The Haffuman encoding given input file content.txt, which contains a paragraph of text, and programming to achieve the above choice of an encoding method, the resulting output of the input file encoded to encode.txt read the results of the encode into the above coding.txt, programming the decoding process (requires the encoding of the Huffman tree, the specific data structures and the preservation of their own design), the decoded output the results to decode.txt )