哈夫曼编码，能后对一个文本，首先剔除非英文字母字符，然后将小写统一转化为大写，再对其进行哈夫曼编码，并输出编码表及带全路径长度-Huffman coding, to a text after the first non-English alphabetic characters removed, and then converted to lowercase unified capital, and then their Huffman encoding, and output coding t