Adv2016/D19.2/Program.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;

namespace D19._2
{
    class Program
    {
        static void Main(string[] args)
        {
            var ba = new List<int>();

            for (var j = 1; j <= int.Parse(args[0]); ++j) ba.Add(j);

            int i = 0;
            while (ba.Count > 1)
            {
                var target = i + ba.Count / 2;
                if (target >= ba.Count) target -= ba.Count;

                ba.RemoveAt(target);

                if (target > i) i++;
                if (i >= ba.Count) i -= ba.Count;
            }

            Console.WriteLine($"The answer is : {ba.First()}");
        }
    }
}