说明：  Huffman codes 􀂄 In telecommunication, how do we represent a set of messages, each with an access frequency, by a sequence of 0’s and 1’s? 􀂄 To minimize the transmission and decoding costs, we may use short strings to represent more frequently used messages. 􀂄 This problem can by solved by using an extended binary tree which is used in the 2- way merging problem.
(Huffman codes )