说明：  利用哈夫曼编码进行通信可以大大提高信道利用率，缩短信息传输时间，降低传输成本。但是，这要求在发送端通过一个编码系统对待传数据预先编码，在接收端将传来的数据进行译码（解码）。对于双工信道（即可以双向传输信息的信道），每端都需要一个完整的编/译码系统。试为这样的信息收发站设计一个哈夫曼编译码系统。
(Using Huffman coding for communication can greatly improve channel utilization, shorten the transmission time and reduce transmission costs. However, this requires the sender to encode the transmitted data by a coding system at the transmitter and decode the data at the receiver. For duplex channels (i.e., channels capable of two-way transmission of information), each end requires a complete codec system. Try to design a Huffman coding and decoding system for such an information transceiver station.)