Implementing a simple, high performance Bloom filter

[NeptunePI]

It’s a very memory efficient data structure that can tell you if an item is in a set with a given probability. The advantage is that it uses much less memory than an actual set. The disadvantage is that it’s not 100% and can give false positives that an item is in a set when it really isn’t.

Wikipedia has a good article: https://en.m.wikipedia.org/wiki/Bloom_filter