Morse code Huffman tree. For some stupid reason, it never occurred to me that Morse code is a Huffman code. In retrospect, it seems obvious that David A. Huffman basically just generalised the concept.
https://snabeltann.no/media/HmzMrQ9mgWWIgohCEfE
@thor
Not really a Huffman tree, since every value has to be a leaf node to disambiguate compressed values. Huffman trees tend to be more asymmetrical.
http://www.binaryessence.com/dct/deG00027.gif
@skypage While Morse code isn't strictly a Huffman code (it relies on pauses to terminate symbols), the basic idea of using binary sequences with shorter codes for common symbols is there. I'm sure that if you had forced telegraphists to not use pauses to separate letters and words, they would've devised Huffman code pretty quickly.
@skypage As for asymmetry, you could choose to make a Huffman tree more balanced if you wanted. At that point, it's more of a prefix code than a true Huffman code, but the principle is the same.
@skypage I think Huffman code is what comes about if you attempt to do a Morse-like code as a uniform stream of binary digits.