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。-From the keyboard characters and each character appear frequency, the frequency as characters of weights, build node tree, then hoffmann for each character coding hoffmann last print characters and corresponding hoffmann coding.