Count number of element in List>

Question

I have a List>. How can I count all the elements in this as if it was a single List in the fastest way?

So far I h

Answer 1

By using LINQ, I think your code is good with a bit changes that no need for .ToList(), just call Count() extension as the following:

int result = listOfLists.SelectMany(list => list).Distinct().Count();