Hat-Trie This a ANSI C99 implementation of the HAT-trie data structure of Askitis and Sinha, an extremely efficient (space and time) modern variant of tries. The version implemented here maps arrays of bytes to words (i.e., unsigned longs), which can be used to store counts, pointers, etc, or not used at all if you simply want to maintain a set of unique strings. For details see, Askitis, N., & Si