Question

I have 20 dictionaries of <Datetime,double> that are mostly for the same range of dates (e.g. feb 24-2012 through june 4 2012). Some dictionaries have extra days, and some are missing days. I want an array of all the unique dates being used.

Currently I’m iterating through all the keys and adding to a hashset to get a unique set, then converting the hashset to an array. Is there a more efficient way?

For the record I also considered iterating through and using the containsKey function of the dictionary and add to a list, or LINQ. My existing process seems to do the trick.

Answer 1

The code you described is the most efficient you can get.
You can do it with less code (and similar efficency) with LINQ:

dicts.SelectMany(d => d.Keys).Distinct().ToArray();