利用huffman编码实现小于4g文件的压缩，先用2进制读写将文件变为2进制码，再通过前缀码构造huffman树，最后存储huffman编码，解码过程反之。-Using huffman coding to achieve less than 4g file compression, first two to read and write binary file into 2 binary code, and then through t