實現最優二叉樹的構造；在此基礎上完成哈夫曼編碼器與譯碼器。 假設報文中只會出現如下表所示的字符：
字符 A B C D E F G H I J K L M N
頻度 186 64 13 22 32 103 21 15 47 57 1 5 32 20 57
字符 O P Q R S T U V W X Y Z ， ．
頻度 63 15 1 48 51 80 23 8 18 1 16 1 6 2
要求完成的系統應具備如下的功能：
1．初始化。從終端（文件）讀入字符集的數據信息，。建立哈夫曼樹。
2．編碼：利用已建好的哈夫曼樹對明文文件進行編碼，并存入目標文件（哈夫曼碼文件）。
3．譯碼：利用已建好的哈夫曼樹對目標文件（哈夫曼碼文件）進行編碼，并存入指定的明文文件。
4．輸出哈夫曼編碼文件：輸出每一個字符的哈夫曼編碼。
I ve written some many years ago dynamic Huffman algorithm to compress and decompress data. It is mainly targeted to data with some symbols occuring more often than the rest (e.g. having some data file consisted of 3 different symbols and their total number of occurence in that file s1(1000), s2(200), s3(30) so the total length of file is 1000+200+30=1230 bytes, it will be encoded assigning one bit to s1 and 2 bits to s2, s3 so the encoded length will be 1*1000+2*(200+30)=1460 bits=182 bytes). In the best case the file consisted of just one symbol will be encoded with compression ratio as 1:8. Huffman coding is used in image compression, however in JPEG2000 arithmetic codec is imployed.
