Calculating nth Fibonacci number with Generic class

fibonacci.cs

using System;

namespace fibonacci_test
{
    class Program
    {
        static int Fib(int n)
        {
            if (n <= 1) return 1;
            return Fib(n - 2) + Fib(n - 1);
        }
        static void Main(string[] args)
        {
            var fib = typeof(Fibonacci<,>);
            var a = typeof(Fib0);
            var b = typeof(Fib1);

            // Console.WriteLine($"0번째 {new Fib0().Value}");
            // Console.WriteLine($"1번째 {new Fib1().Value}");
            for (int i = 2; i <= 20; i++)
            {
                var fib_i = fib.MakeGenericType(a, b);
                a = b;
                b = fib_i;
                // dynamic instance = Activator.CreateInstance(fib_i);
                // Console.WriteLine($"{i}번째 {instance.Value}");
            }

            dynamic fib20 = Activator.CreateInstance(b);
            var prev = DateTime.Now;
            int val = fib20.Value;
            var now = DateTime.Now;

            Console.WriteLine($"제너릭 방식으로 : {(now - prev).TotalMilliseconds} ms 걸림");

            prev = DateTime.Now;
            Fib(20);
            now = DateTime.Now;

            Console.WriteLine($"재귀함수 방식으로: {(now - prev).TotalMilliseconds} ms 걸림");
        }
    }
    

    class Fibonacci { public Fibonacci() { } }

    class Fibonacci<P2, P1> : Fibonacci where P1 : new() where P2 : new()
    {
        public int Value => ((dynamic)new P1()).Value + ((dynamic)new P2()).Value;
    }

    class Int1 : Fibonacci<Fibonacci, Fibonacci>
    {
        public new int Value => 1;
    }

    class Fib0 : Int1 { }
    class Fib1 : Int1 { }
    class Fib2 : Fibonacci<Fib0, Fib1> { }
    class Fib3 : Fibonacci<Fib1, Fib2> { }
    class Fib4 : Fibonacci<Fib2, Fib3> { }
    class Fib5 : Fibonacci<Fib3, Fib4> { }
    class Fib6 : Fibonacci<Fib4, Fib5> { }
    class Fib7 : Fibonacci<Fib5, Fib6> { }
    class Fib8 : Fibonacci<Fib6, Fib7> { }
    class Fib9 : Fibonacci<Fib7, Fib8> { }
    class Fib10 : Fibonacci<Fib8, Fib9> { }
}

result

제너릭 방식으로 : 3251.0026 ms 걸림
재귀함수 방식으로: 0.498 ms 걸림