Check for missing number in sequence

algorithm, c#, linq

Solution

var list = new List<int>(new[] { 1, 2, 4, 7, 9 });
var result = Enumerable.Range(0, 10).Except(list);

Problem

I have an `List<int>` which contains 1,2,4,7,9 for example. I have a range from 0 to 10. Is there a way to determine what numbers are missing in that sequence? I thought LINQ might provide an option but I can't see one In the real world my List could contain 100,000 items so performance is key

Original source