通过该程序实现huffman编码，解码。输入一段字符串，统计字符出现频率，输出huffman编码。输入一段编码，根据预先设定的解码方式进行解码。-Through the process to achieve huffman encoding and decoding. Enter a string, statistical character frequency, the output huffman coding. Enter a code, based on pre-set decoding