I should have specified earlier: Google Sparsehash also contains Densehash which is optimised for speed, not space. It, however, is also more space efficient th

I should have specified earlier: Google Sparsehash also contains Densehash which is optimised for speed, not space. It, however, is also more space efficient than most other hash implementations. Check out dense_hash_map[1] [1]: http://sparsehash.googlecode.com/svn/trunk/doc/implementation.html http://sparsehash.googlecode.com/svn/trunk/doc/implementatio...