In his 1973 book Systematic Programming: An Introduction, Niklaus Wirth gives the following problem as exercise 15.12: Develop a program that generates in ascending order the least 100 numbers of the set M, where M is defined as follows: a) The number 1 is in M. b) If x is in M, then y = 2 * x + 1 and z = 3 * x + 1 are also in M. c) No other num…

gistfile1.cs

//http://programmingpraxis.com/2012/12/07/wirth-problem-15-12/

namespace Wirth_Problem_15._12
{
    class Program
    {
        static int MAX_SIZE = 10000;
        static byte?[] aWrith = new byte?[MAX_SIZE];

        static void Main(string[] args)
        {  
            for (int i = 0; i < 100; i++)
            {
                int nextNumber = GetNext();

                aWrith[nextNumber] = 1;
                aWrith[nextNumber * 2 + 1] = 0;
                aWrith[nextNumber * 3 + 1] = 0;
            }

            for (int i = 0; i < MAX_SIZE; i++)
            {
                if (aWrith[i] == 1)
                {
                    System.Console.Write(String.Format("{0},", i));
                }
            }

        }

        static int GetNext()
        {
            for (int i = 1; i < MAX_SIZE; i++)
            {
                if (aWrith[i] == 0)
                {
                    return i;
                }               
            }

            return 1;
        }

    }
}