Huffman coding is a method of encoding characters based on their frequency. Each letter is assigned a variable-length binary string, such as 0101 or 111110, where shorter lengths correspond to more common letters. To accomplish this, a binary tree is built such that the path from the root to any leaf uniquely maps to a character. When traversing the path, descending to a left child corresponds to a 0 in the prefix, while descending right corresponds to 1.
'((A . 5)
(B . 25)
(C . 7)
(D . 15)
(E . 4)
(F . 12))
'((F . #*00)
(D . #*01)
(C . #*100)
(E . #*1010)
(A . #*1011)
(B . #*11))
ccl -e "(ql:quickload :huffman/tests)" -e "(asdf:test-system :huffman)" -e "(quit)"