An implementation of using the x-fast trie for fast predecessor search. Illustrated with an example of the problem of searching for the closest movie release meeting some arbitrary condition.
Rather than getting all theoretical, let us start with a simple and illustrative example. With movie and tv show titles such as X-files, X-men and American History X, we have a trope of X standing for anything misterious (and heavily implied to be hip). How often are movies with such titles released? What was the first X-movie released since your birth?
To find out, let us build the X-fast trie index for such X-titled movies by the year of release.
Here is a plot of what we get: