閏年を論理演算じゃなく判定するやつ！＞＜

uruudoshi.cs

using System;
//
// 自信ない＞＜；
// 
namespace uruudoshi
{
    class Program
    {
        static void Main(string[] args)
        {
            System.Console.WriteLine("年を入力してEnterを押すと閏年かわかるよ！！！＞＜");
            while (true)
            {
                TestOne();
            }
        }

        private static void TestOne()
        {
            string str = System.Console.ReadLine();

            int year = 0;

            if (int.TryParse(str, out year))
            {
                int result = Uruudoshi(year);

                System.Console.WriteLine($"");
                System.Console.WriteLine($"{year}年は");
                if (result != 0)
                {
                    System.Console.WriteLine("閏年！！！＞＜");
                }
                else
                {
                    System.Console.WriteLine("ふつうの年");
                }
                System.Console.WriteLine("result: " + result);
            }
            else
            {
                System.Console.WriteLine("整数を入力してね！＞＜");
            }
        }
        /// <summary>
        /// 閏年の時はゼロ以外、閏年じゃない時にはゼロを返すやつ＞＜
        /// </summary>
        /// <param name="year"></param>
        /// <returns>0 is common year, not 0 is leap year</returns>
        public static int Uruudoshi(int year)
        {
            return (((year + 1) % 4) * ((year + 2) % 4) * ((year + 3) % 4) * (year % 100))
                + (((year + 1) % 4) * ((year + 2) % 4) * ((year + 3) % 4)) *
                ((year - (year % 100)) *
                ((((year - (year % 100)) + 100) / 100) % 4) *
                ((((year - (year % 100)) + 200) / 100) % 4) *
                ((((year - (year % 100)) + 300) / 100) % 4));
        }



    }
}