Rework C++ implementation for Huffman encoding

[mika314]

• Make implementation shorter and easier to understand
• Make namespace hierarchy flat
• Combine Leaf and Branch in one class Node for the tree
• Make codebook explicit
• Use std::string for string_to_encode
• Remove noise (delete function with_new_bit() for instance)
• Use unordered map for weights instead of vector
• Instead inserting to the orphan array, sort it on every iteration (debatable)
• Remove structure for cacheing bits for character, calculate it every time
• Remove error handling
• Change the encoding interface: encode() and decode() instead huffman::encode_string() and encoded.decoded()

[Butt4cak3]

Could you please provide some explanation for why you think this rework was necessary and why your version is better than the current?

[mika314]

Updated commit message and message in PR to emphasize why rework is needed.

[zsparal]

I like the changes but I think the rest of the C++ code samples try to follow the standard library's style, which would mean using snake_case for types and variables

[mika314]

@Gustorn no problem, I'll rename Node and Codebook to lower case.

[mika314]

@Gustorn changes with snake_case are pushed

[zsparal]

I don't think storing which branch we're on is necessary.

[mika314]

What do you mean? It used here:

compressed_char.push_back(node->branch != node::branch::left);

https://github.com/antonte/algorithm-archive/blob/71c0d4295d4a892c91e1da64fdb7feaa9ea56dd3/contents/huffman_encoding/code/c%2B%2B/huffman.cpp#L83

[zsparal]

Since you're storing a parent pointer anyway, it's trivial to write a function that tests whether the current node is a left or a right child. This implementation of the Huffman algorithm is inefficient enough as it is, no need to make it worse by bloating the node struct

[leios]

Hey guys. What's the status on this PR? It looks like the review was completed; however, it was not yet merged into the AAA. Can I dismiss the review @Gustorn and merge?

[Gathros]

Another stale pull request.