A Method for the Construction of Minimum-Redundancy Codes

https://cs.nyu.edu/~roweis/csc310-2006/extras/huffman_1952_minimum-redundancy-codes.pdf

哈夫曼树_百度百科 https://baike.baidu.com/item/%E5%93%88%E5%A4%AB%E6%9B%BC%E6%A0%91