SuperClass for 22-solve by MrPaul

public class Calculation
    {
        public delegate int Command(int x);

        private List<Command> commands = new List<Command>();
        public void RegisterCommand(Command command) => commands.Add(command);

        public long GetCount(int begin, int[] checkPointsOrder, int[] deprecated = null, Func<int, bool> stop = null)
        {
            if (checkPointsOrder == null || checkPointsOrder.Length == 0) return 0;
            if (deprecated == null) deprecated = new int[]{ };
            if (stop == null) stop = x => false;

            SortedSet<int> depr = new SortedSet<int>(deprecated);
            int Run(int x, int currEnd)
            {
                if (depr.Contains(x) || stop(x)) return 0;
                if (x == currEnd) return 1;
                try
                {
                    return commands.Select(f => Run(checked(f(x)), currEnd)).Sum();
                }
                catch(Exception)
                {
                    return 0;
                }
            }

            long result = 1;

            foreach(int end in checkPointsOrder)
            {
                result *= Run(begin, end);
                begin = end;
            }

            return result;
        }
    }