Yeah, my first thought was that this was a job for a trie. You can inspect your input character by character, and you can rule out most strings by the first byt

Yeah, my first thought was that this was a job for a trie. You can inspect your input character by character, and you can rule out most strings by the first byte since it must be h, f or w. If your set is small and static, you can hard-code the trie and it will be superfast, but a long as you can fail fast when checking each character (so don’t use the default hasher in Rust), you can check for matches quickly and easily.