Fastest way to Remove Duplicate Value from a list<> by lambda

Question

what is fastest way to remove duplicate values from a list. Assume List longs = new List { 1, 2, 3, 4, 3, 2, 5 }; So I am interesting in

Answer 1

The easiest way to get a new list would be:

List unique = longs.Distinct().ToList();

Is that good enough for you, or do you need to mutate the existing list? The latter is significantly more long-winded.

Note that Distinct() isn't guaranteed to preserve the original order, but in the current implementation it will - and that's the most natural implementation. See my Edulinq blog post about Distinct() for more information.

If you don't need it to be a List, you could just keep it as:

IEnumerable unique = longs.Distinct();

At this point it will go through the de-duping each time you iterate over unique though. Whether that's good or not will depend on your requirements.