Guidの部分文字列が被るかどうかのテスト(コンソールアプリ)

Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            var count = 10000;
            if (args.Length > 0) {
                count = Convert.ToInt32(args[0]);
            }
            var map = new Dictionary<string, int>();
            for (int i = 0; i < count; i++)
            {
                var guid = Guid.NewGuid();
                var sub = guid.ToString().Substring(0, 8);
                if (map.ContainsKey(sub))
                {
                    map[sub] += 1;
                }
                else
                {
                    map[sub] = 1;
                }
            }

            foreach (var p in map)
            {
                if (p.Value > 1)
                {
                    Console.WriteLine("{0}:{1}",p.Key,p.Value);
                }
            }
        }
    }
}