Remove duplicates from a List in C#

Question

Anyone have a quick method for de-duplicating a generic List in C#?

Answer 1

If you don't care about the order you can just shove the items into a HashSet, if you do want to maintain the order you can do something like this:

var unique = new List();
var hs = new HashSet();
foreach (T t in list)
    if (hs.Add(t))
        unique.Add(t);

Or the Linq way:

var hs = new HashSet();
list.All( x =>  hs.Add(x) );

Edit: The HashSet method is O(N) time and O(N) space while sorting and then making unique (as suggested by @lassevk and others) is O(N*lgN) time and O(1) space so it's not so clear to me (as it was at first glance) that the sorting way is inferior (my apologies for the temporary down vote...)