7 ms·
A hash table is more than compact enough. It should work fine even at high load factors (80%/90%) given a decent hash scheme (eg. Robin Hood hashing) which mean
by Veedrac 11y ago
A hash table is more than compact enough. It should work fine even at high load factors (80%/90%) given a decent hash scheme (eg. Robin Hood hashing) which means you need only 4GB memory. It's random access and on average should have one cache miss per lookup. Updating is rather trivial.
- bilalhusain 11y agoSounds promising. Little bit concerned on the computational cost of hashing function. Gotta explore this option!
- Veedrac 11y agoI wouldn't be worried about hashing, either, given you effectively want to hash a 34 bit integer to a ⌈log 4e8⌉ = 29 bit integer. An easy way is to take a 32 to 32 bit hash (eg. http://stackoverflow.com/a/12996028/1763356 http://stackoverflow.com/a/12996028/1763356), calculate hash(top 32 bits) ^ hash(bottom 32 bits) and take the bottom 29 bits of that. I wouldn't be surprised if you can do this in less time than an integer division.