using System;

​

public class Program

{

    public static void Main()

    {

        //digits 1-6 (ddMMyy)

        string randomDateOfBirth = GetRandomDate(fromDate: new DateTime(1950, 1, 1), toDate: new DateTime(2021, 1, 1)).ToString("ddMMyy");

        //digits 7-10 (SSSS)

        string randomNumberSequence;

        bool female = NextBoolean();

        if (female)

        {

            //even number sequence (based on assignment of social security numbers to women table https://da.wikipedia.org/wiki/CPR-nummer#Hvordan_personnumre_tildeles)

            randomNumberSequence = GenerateRandomCPRNumberSequence(onlyRandomEvenNumbers: true);

        }

        else

        {

            //odd number sequence (based on assignment of social security numbers to men table https://da.wikipedia.org/wiki/CPR-nummer#Hvordan_personnumre_tildeles)

            randomNumberSequence = GenerateRandomCPRNumberSequence(onlyRandomEvenNumbers: false);

        }

​

        Console.WriteLine(randomDateOfBirth + randomNumberSequence);

    }

​

    public static DateTime GetRandomDate(DateTime fromDate, DateTime toDate)

    {

        var range = toDate - fromDate;

        var randomTimeSpan = new TimeSpan((long)(new Random(Guid.NewGuid().GetHashCode()).NextDouble() * range.Ticks));

        return fromDate + randomTimeSpan;

    }

​

    private static string GenerateRandomCPRNumberSequence(bool onlyRandomEvenNumbers)

    {

        int newRandomNumber;

        //

        if (onlyRandomEvenNumbers)

        {

            do

            {

                newRandomNumber = GenerateRandomNumber();

            }

            while (newRandomNumber % 2 != 0);

        }

        else

        {

            do

            {

                newRandomNumber = GenerateRandomNumber();

            }

            while (newRandomNumber % 2 == 0);

        }

​

        if (newRandomNumber < 100)

        {

            return $"000{newRandomNumber}";

        }

        else if (newRandomNumber > 99 && newRandomNumber < 1000)

        {

            return $"00{newRandomNumber}";

        }

        else

        {

            return newRandomNumber.ToString();

        }

    }

​

    private static int GenerateRandomNumber(int min = 1, int max = 9999)

    {

        return new Random(Guid.NewGuid().GetHashCode()).Next(min, max);

    }

​

    public static bool NextBoolean()

    {

        return new Random(Guid.NewGuid().GetHashCode()).Next() > (int.MaxValue / 2);

    }

}