Suppose that I have a trie data structure holding a number of strings. To look up a string in the trie, I would start at the root and follow the pointer labeled with the appropriate characters of the string, in order, until I arrived at a given node.
Now suppose that I want to build a “reverse trie” for the same set of strings, where instead of looking up strings by starting with the first character, I would look up strings by starting with the last character.
Is there an efficient algorithm for turning tries into reverse tries? In the worst case I could always list off all the strings in the trie and then insert them one-at-a-time into a reverse trie, but it seems like there might be a better, more clever solution.
But the nodes in your trie are in essentially random order, if your ordering criteria is based on the strings’ reverse. That is, given the sequence
[aardvark, bat, cat, dog, elephant, fox], which are in alphabetical order, reversing the words would not give you the sequence[xof, tnahpele, god, tac, tab, kravdraa].In other words, there’s no “more clever solution” than to build your reverse trie.