using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        List<Project> projs = new List<Project>();

        for (int i = 0; i < 10000; i++)

            projs.Add(new Project() { ProjectNo = "000" + i });

​

        for (int i = 0; i < 10; i++)

            projs.Add(new Project() { ProjectNo = "000" + i });

​

        Console.WriteLine("RemoveDuplicates");

        Console.WriteLine("-----------------------------");

        Console.WriteLine("Pre count:" + projs.Count());

        Stopwatch sw = Stopwatch.StartNew();

        projs = RemoveDuplicates(projs);

        sw.Stop();

        Console.WriteLine("Post count:" + projs.Count());

        Console.WriteLine("Time taken: {0} ms\n\n", sw.Elapsed.TotalMilliseconds);

    }

​

    public static List<Project> RemoveDuplicates(List<Project> projects)

    {

        return new HashSet<Project>(projects).ToList();

    }

​

    public class Project

    {

        public string ProjectNo { get; set; }

        public Project() { }

        public override bool Equals(object other)

        {

            var otherObject = other as Project;

            return otherObject != null && otherObject.ProjectNo == ProjectNo;

        }

        public override int GetHashCode()

        {

            return ProjectNo.GetHashCode();

        }

    }

}