Huffman codes

　　Huffman’s greedy algorithm uses a table giving how often each character occurs (i.e., its frequency) to build up an optimal way of representing each character as a binary string. 

　　we interpret the  binary codeword for a character as the simple path from the root to that character ,where 0 means go to the left child and 1 means  go to the right child .

we interpret the  binary codeword

for a character as the simple path from the root to that character ,where 0 means go to the left child and 1 means  go to the right child .

Note that these are not binary search trees, since the leaves need not appear in sorted order and internal nodes do not contain character keys.

an optimal code for a  file is always represented by a fully binary tree ,in which every nonleaf has two children .

the tree for an optimal prefix code has exactly |C| leaves ,one for each letter of the alphabet ,ash exactly |c|-1interanl nodes .

what is the meaning 

？

when we merge two objects ,the result is a new object whose frequency is the sum of the frequencies of the two object that were merged .