using System;

using System.Collections.Generic;

using System.Linq;

using System.Diagnostics;

​

public class Exercise3

{

    public static void Main()

    {

        var employees = new List<Employee>();

        for (var i = 0; i < 20000; i++)

        {

            employees.Add(new Employee() { Id = i, DepartmentId = i });

        }

        var departments = new List<Department>();

        for (var i = 0; i < 20000; i++)

        {

            departments.Add(new Department() { Id = i });

        }

        var stopwatch = Stopwatch.StartNew();

        var results = Run(employees, departments);

​

        if (results.Count() != 20000)

            throw new System.Exception("wrong answer");

        stopwatch.Stop();

​

        Console.WriteLine(stopwatch.ElapsedMilliseconds);

    }

​

    //ONLY CHANGE THIS METHOD

    public static IEnumerable<EmployeeDepartment> Run(IEnumerable<Employee> employees, IEnumerable<Department> departments)

    {

​

        var results = new List<EmployeeDepartment>();

        foreach (var employee in employees)

        {

            var res = new EmployeeDepartment()

            {

                Employee = employee,

                Department = departments.First(department => department.Id == employee.DepartmentId)

            };

            results.Add(res);

        }

​

        return results;

    }

}

​

public class Employee

{

    public int Id { get; set; }

    public int DepartmentId { get; set; }

}

​

public class Department

{

    public int Id { get; set; }

}

​

public class EmployeeDepartment

{

    public Department Department { get; set; }

    public Employee Employee { get; set; }

}