哈夫曼编码:从键盘输入若干字符及每个字符出现的频率，将字符出现的频率作为结点的权值，建立哈夫曼树，然后对各个字符进行哈夫曼编码，最后打印输出字符及对应的哈夫曼编码。-Huffman coding: the frequency of occurrence of several characters inputted the keyboard and for each character, the character appears as a frequency node weights, the