Pre-processing was designed to mark the significance of all nodes and main-processing to finish listless zerotree coding. 预处理完成对所有节点显著性的标注，主处理完成无链表的零树编码。
When coding the wavelet-trees, zerotree is using neatly, which improves the compression efficiency. 在对小波树编码时，灵活运用了零树的概念，提高了压缩效率。
