Question

I need an algorithm to store a key/value pair, where the key is an Int64. I’m currently using a sorted IntList (same as a TStringList, but stores int64s). This gives me O(log n) for search, Insert and delete operations. Since I don’t ever need the items sorted, this is a little inefficient. I need some kind of hashtable for O(1) operations. The problem is that most implementations I can find assume the key is a string. Now I could obviously convert the Int64 key to a string, but this does seem wasteful. Any ideas?

I do not know the number of items before they are entered to the data structure.

I also should add that I have implemented the same component in .net, using Dictionary, and it’s adding the items that is so much faster in the .net version. Once the data structure is setup, traversals and retrievals are not that bad in comparison, but it’s insertion that is killing me.

Answer 1

Delphi 2009 and later has added Generics.

So starting Delphi 2009, you can implement your key/value pair in a similar manner as you do in .NET using a TDICTIONARY.

And TDICTIONARY in Delphi uses a hash table table and has O(1) operations.