c#控制台应用程序-“进入指定日期检查出星期几”

这涉及一个算法：

            Console.WriteLine("**************************");
            Console.WriteLine("输入指定年月日查询出星期几");
            Console.WriteLine("By:YYS");
            Console.WriteLine("今天是{0}年{1}月{2}日 星期{3}", DateTime.Now.Year,DateTime.Now.Month, DateTime.Now.Day, (int)DateTime.Now.DayOfWeek);
            Console.WriteLine("**************************");

            Console.ForegroundColor = ConsoleColor.Red;
            Console.WriteLine("请输入年:");
            int y = System.Int32.Parse(Console.ReadLine());
            Console.WriteLine("请输入月");
            int m = System.Int32.Parse(Console.ReadLine());
            Console.WriteLine("请输入日");
            int d = System.Int32.Parse(Console.ReadLine());
            int week = (d + 2 * m + 3 * (m + 1) / 5 + y + y / 4 - y / 100 + y / 400 + 1) % 7;

            Console.WriteLine("{0}年{1}月{2}日是星期{3}",y,m,d,week);
            Console.ReadKey();