How to find the parent list using Linq Query for below

Question

   

I Have classes

public class User

{

Int UserId;

String UserName

products List

}

 

public class Product

{

int ProductId;

int ProductName;

}

 

var data = new List();

 

data.Add(1, new List { new Product {prdouctId= 1, ProductName = "Name1"} , new Product {ProductId=2, ProductName="Name2"}}

 

data.Add(2, new List { new Product {prdouctId= 2, ProductName = "Name2"} , new Product {ProductId=3, ProductName="Name3"}}

 

data.Add(3, new List { new Product {prdouctId= 4, ProductName = "Name4"} , new Product {ProductId=2, ProductName="Name1"}} 

 

How we get the users List with Linq query who are mapped product wise

 

Expected Result:

---------------------- 

ProdcutId     UsersId

1                  {1,3}

2                  {1,2,3}

3                 {2,3}