用lz77算法进行压缩，对得到的结果再使用huffman编码的方法进行压缩。分别对lz77和huffman编码的原理进行说明。 -Lz77 algorithm to compress the results obtained using huffman encoding method to compress. Lz77 and huffman encoding principle is described.

C语言基础实现大小写字母转换，实现哈夫曼编码。对学习C用处大-C language based case conversion, Huffman encoding. Useful for learning C