How do I do an integer list intersection while keeping duplicates?

Question

I\'m working on a Greatest Common Factor and Least Common Multiple assignment and I have to list the common factors. Intersection() won\'t work because that removes duplicat

Answer 1

I wrote this extension to solve the problem:

public static IEnumerable Supersect(this IEnumerable a, ICollection b)
              => a.Where(t => b.Remove(t));

example:

var a = new List { 1, 2, 2, 2, 3, 3, 4, 5 };
var b = new List { 1, 1, 2, 2, 3, 3, 3, 4, 4};

var result = a.Supersect(b);

result:

{ 1, 2, 2, 3, 3, 4 }