为得到使电文总长最短的二进制前缀编码，则以n种字符出现的频率作权，设计一棵Huffman树，求出给定权值的字符对应的Huffman编码。-enable the message to be chief of the shortest prefix binary coding, while the n characters of frequencies for the right to design a Huffman tree, obtained the right to set the value of the characters in the corresponding Huffman coding.