根据给定的信源概率分布，编程实现霍夫曼编码和二次扩展信源霍夫曼编码，并和信源的熵进行比较，体会霍夫曼编码的编码效果。(According to the given probability distribution of the source, Hoffman encoding and two extended source Hoffman coding are programmed and compared with the entropy of the source to realize the coding effect of Hoffman encoding.)