huffman tree 问题描述：设一份电文中有不同出现频率的字符，为了提高电文的输入和翻译效率，必须有一套简短而又不会产生歧义的字符代码。试根据哈夫曼算法，对电文中的不同字符，构造出一棵哈夫曼树，对每个字符进行编码。-Huffman tree Problem descr iption : Let a message different frequency of the characters, in order to enhance the input and message translation efficiency, we must have a brief but no ambiguity of the characters code. Examination under Huffman algorithm, the message of characters, construct a Huffman tree for each character coding.