MyDI.cs

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

namespace ConsoleApp
{
    public static class MyServiceProvider
    {
        private static readonly Dictionary<Type, Type> Store = new Dictionary<Type, Type>();

        public static T GetService<T>()
        {
            if (Store.ContainsKey(typeof(T)))
            {
                return (T) Compose(Store[typeof(T)]);
            }

            return default(T);
        }

        private static object Compose(Type type)
        {
            var constructorInfo = 
                type.GetConstructors()
                    .FirstOrDefault(
                        constructor => 
                            constructor
                                .GetParameters()
                                .All(parameter => Store
                                .Any(item => item.Key == parameter.ParameterType)));

            if (constructorInfo == null)
            {
                return Activator.CreateInstance(Store[type]);
            }

            var parameters = constructorInfo
                .GetParameters()
                .Select(parameter => Compose(Store[parameter.ParameterType]))
                .ToArray();

            return constructorInfo.Invoke(parameters);
        }

        public static void Register<T>(Type type)
        {
            Store[typeof(T)] = type;
        }
    }
}