huffman 树的创建和实现对元素进行huffman编码，本次试验在程序设计方面较之前次实验容易些，但在尝试用动态申请结构数组空间来设计程序时却没有成功-huffman tree to create and realize huffman coding of elements, the test procedure design easier than the previous experiment, but try to use the dynamic structure of the ar