Is there a way to restore frequency array from Huffman tree?

Question

Most people, when they implement study Huffman algorithm, prefer to store frequency array, not Huffman tree. But sometimes I would like to store Huffman tree. For example, It allows immediately decode data.

Unfortunately, I do not know, how to restore frequency array from Huffman tree. Furthermore, I do not know, it is possible or not.

Answer 1

It is not clear why you want to restore the frequency array. As you said, the tree is all you need to decode. (You don't even need to send the tree — you can just send the number of bits for each symbol, and generate a canonical Huffman code from that.)

You do not have enough information to recover the original frequency array. However you can easily construct a frequency array that would reproduce that tree. Make the longest codes frequency 1, codes with one bit less frequency 2, two bits less frequency 4, and so on.

Answer 2

IMO when you have the frequency you can simply reconstruct the tree with the same function, for example greater or less.