You will find all you need here: http://en.wikipedia.org/wiki/Huffman_coding
See also the referenced to examples in this article.
Now, the question is not quite correct: the algorithm is abstracted from the content you want to compress. But it makes some sense, because a linked list is something which resides in memory, so you will need to develop serialization
for your data. Please see:
] (yes, I would recommend boost serialization).
Basically, this is all you need.