利用赫夫曼树的编码思想，构造一个完整的赫夫曼编码系统。



要求如下：



①从键盘读入字符集大小n，以及n个字符和n个权值，建立赫夫曼树，然后对赫夫曼树进行编码，输出结果。



②使用上述字符集创建一个任意的明文，对该明文进行编码，输出该明文的电文序列。



③利用上述创建的编码集合，输入任意的电文序列，输出该电文的明文。-Use Huffman coding tree thinking, construct a complete Huffman coding system.



Requirements are as follows:



① reading character set size n, and n and n characters from the keyboard weights, Huffman tree, and the tree Huffman encoded output.



② the character set used to create an arbitrary plaintext, the plaintext is encoded output sequence of the plaintext message.



③ collection created by the encoding above, enter any text sequence, the output of the plaintext message.