本程序主要是来实现赫夫曼编码的问题。用户可以输入键盘中的任意字符，长度为任意长，字符输入顺序不限，且允许出现重码,可以对任意长的字符串可进行编码

按顺序打印出对应输入字符串的哈夫曼编码-This procedure is mainly to achieve the Huffman coding problem. Users can enter any keyboard characters, the length of arbitrary long input sequence of characters open, and allow re-code, can be a long string of arbitrary code can be printed by order of the corresponding input of the Huffman encoded string