C# 多线程协同完成一个任务

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

namespace ConsoleApplication3
{
    class Program
    {
        static long Sum=0;
        static object mylock;
        static void Main(string[] args)
        {
            long n = 0;
            long s1 = DateTime.Now.Ticks;
            for (int i = 0; i <= 100; i++)
            {
                n += i;
                Thread.Sleep(10); 
            }
            long s2 = DateTime.Now.Ticks;
            Console.Write("----------------单线程运行-------------------\nsum:" + n + "\n\r所花时间(纳秒):" + (s2 - s1)+"\n");
            Console.Write("----------------双线程运行-------------------\n");
            Thread t1 = new Thread(add1);
            Thread t2 = new Thread(add2);
            mylock = new object();
            s1 = DateTime.Now.Ticks;
            t1.Start();
            t2.Start();
            t1.Join();
            t2.Join();
            s2 = DateTime.Now.Ticks;
            Console.Write("sum:" + n + "\n\r所花时间(纳秒):" + (s2 - s1));
            Console.ReadKey();
        }
        static void add1()
        {
            long n = 0;
            for (int i = 0; i <= 50; i++)
            {
                n += i;
                Thread.Sleep(10);
            }
            Monitor.Enter(mylock);
            Sum += n;
            Console.Write("线程一运行完毕,Sum:" + Sum+"\n");
            Monitor.Exit(mylock);
           
            
        }
        static void add2()
        {
            long n = 0;
            for (int i = 51; i <= 100; i++)
            {
                n += i;
                Thread.Sleep(10);
            }
            Monitor.Enter(mylock);
            Sum += n;
            Console.Write("线程二运行完毕,Sum:" + Sum + "\n");
            Monitor.Exit(mylock);
           
        }
    }
}