I'm trying to create a LINQ query (or queries) that count the total number of occurences of a combinations of items in one list that exist in a different list. For example, take the following lists:

CartItems                  DiscountItems
=========                  =============
AAA                        AAA
AAA                        BBB
AAA
BBB
BBB
CCC
CCC
DDD

The result of the query operation should be 2 since I can find two combinations of AAA and BBB (from DiscountItems) within the contents of CartItems.

My thinking in approaching the query is to join the lists together to shorten CartItems to only include items from DiscountItems. The solution would be to find the CartItem in the resulting query that occurs the least amount of times, thus indicating how many combinations of items exist in CartItems.

How can this be done?

Here's the query I already have, but it's not working. query results in an enumeration with 100 items, far more than I expected.

    Dim query = From cartItem In Cart.CartItems
                Group Join discountItem
                    In DiscountGroup.DiscountItems
                    On cartItem.SKU Equals discountItem.SKU
                    Into Group
                Select SKU = cartItem.SKU, CartItems = Group

    Return query.Min(Function(x) x.CartItems.Sum(Function(y) y.Quantity))