On Sat, Dec 31, 2011 at 7:03 AM, Stephen J. Turnbull <stephen@xemacs.org> wrote:
While the dictionary probe has to start with a hash for backward
compatibility reasons, is there a reason the overflow strategy for
insertion has to be buckets containing lists?  How about
double-hashing, etc?

This won't help, because the keys still have the same hash value. ANYTHING you do to them after they're generated will result in them still colliding.

The *only* thing that works is to change the hash function in such a way that the strings end up with different hashes in the first place.  Otherwise, you'll still end up with (deliberate) collisions.

(Well, technically, you could use trees or some other O log n data structure as a fallback once you have too many collisions, for some value of "too many".  Seems a bit wasteful for the purpose, though.)