深夜脑洞，写了一个可以推算火车票身份证号码的小程序

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace Geyunfei.CheckID{    class PRogram    {        static int[] a = new int[] { 7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2 };        static char[] b = new char[] { '1', '0', 'X', '9', '8', '7', '6', '5', '4', '3', '2' };        static int index = 0;        static void Main(string[] args)        {            System.Console.WriteLine("输入火车票上的身份证号:");            String a = System.Console.ReadLine();            var year = int.Parse(a.Substring(6, 4));            var beginDate = new DateTime(year, 1, 1);            var chk = a.Substring(14);            int days = 365;            if (DateTime.IsLeapYear(year))                days++;            for(int i =0;i<days; i++)            {                var chkDate = beginDate.AddDays(i).ToString("MMdd");                var id = a.Substring(0, 10) + chkDate + chk;                CheckID(id);            }                   }        private static void CheckID(string id)        {            int sum = 0;            for(int i = 0; i < 17; i++)            {                sum += int.Parse(id[i].ToString()) * a[i];            }            var chk = b[sum % 11];            if (chk == id[17])            {                index++;                Console.WriteLine(getAstro(int.Parse(id.Substring(10,2)),int.Parse(id.Substring(12,2)))+ index.ToString() +" "+id);            }        }        private static String getAstro(int month, int day)        {            String[] starArr = {"魔羯座","水瓶座", "双鱼座", "牡羊座",        "金牛座", "双子座", "巨蟹座", "狮子座", "处女座", "天秤座", "天蝎座", "射手座" };            int[] DayArr = { 22, 20, 19, 21, 21, 21, 22, 23, 23, 23, 23, 22 };  // 两个星座分割日            int index = month;            // 所查询日期在分割日之前，索引-1，否则不变            if (day < DayArr[month - 1])            {                index = index - 1;            }            index = index % 12;            // 返回索引指向的星座string            return starArr[index];        }    }}