 Ternary prefix code

A prefix code whose codewords use a three-symbol alphabet, conventionally $\{0,1,2\}$. No complete codeword is a prefix of another, permitting sequential decoding by following a code tree to a tree leaf. Its expected codeword length is ${\sum }_i{p}_i|c(i)|$ trits per source symbol. For source probabilities $(1/2,1/4,1/8,1/8)$, the codewords $(0,1,20,21)$ give expected codeword length $5/4$ trits.