using System;

using System.Linq;

using System.Collections;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

​

        //Initializing a collection of 4 Employees fromthree Different departments <Name of Employee, Dept ID>

        List<KeyValuePair<string, int>> EmployeeDept = new List<KeyValuePair<string, int>> {

            new KeyValuePair<string, int> ("Gates",2),

            new KeyValuePair<string, int> ("Nadella",2),

                new KeyValuePair<string, int> ("Mark",3),

            new KeyValuePair<string, int> ("Pichai",4)

        };

        //Filter the Employees belongs to these department

        int[] deptToFilter ={3,4};

        //Approach 1 - Using COntains Method

        Console.WriteLine ("Approach 1 - Using Contains");

        Console.WriteLine ("==========================================");   

        var filterdByContains = EmployeeDept.Where(emp => deptToFilter.Contains(emp.Value));

        foreach (var dept3and4employees in filterdByContains)

        {

            Console.WriteLine(dept3and4employees.Key+" - "+dept3and4employees.Value);

        }

        //Approach 2 Using Join

        Console.WriteLine ("\n\nApproach 2 - Using Join");

        Console.WriteLine ("==========================================");   

        var filteredByJoin = EmployeeDept.Join(

            deptToFilter,

            empdept => empdept.Value, 

            filterdept => filterdept, 

            (empdep,filddep) => new KeyValuePair<string, int>(empdep.Key, empdep.Value)

        );

        foreach (var dept3and4employees in filteredByJoin)

        {

            Console.WriteLine(dept3and4employees.Key+" - "+dept3and4employees.Value);

        }

    }

}