MultiEntryPointSmartContract.cs

namespace multi {
    using System;
    using System.Linq;
    public class MultiEntryPointSmartContract : SmartContract {      
        public object Main (string name, params object[] parameters) {
            if (name == null || name.Trim().Length == 0) {
                throw new ArgumentNullException("The method name parameter can not be empty");
            }
            var methods = this.GetType().GetMethods().Where(x => x.Name == name && x.GetParameters().Length == parameters.Length);
            if (methods.Count() == 0) {
                throw new ArgumentException(string.Format("No method found with the name '{0}' and {1} parameters", name, parameters.Count()));
            }
            if (methods.Count() > 1) {
                throw new ArgumentException(string.Format("More than one method found with the name '{0}' and {1} parameters", name, parameters.Count()));
            }
            return methods.First().Invoke(null, parameters);
        }
    }
}

MultiOperationSmartContract.cs

namespace multi {
    using System;
    using System.Linq;
    // The usual way to do it
    public class MultiOperationSmartContract : SmartContract {
        public static object Main (string name, params object[] parameters) {
            if (name == null || name.Trim().Length == 0) {
                throw new ArgumentNullException("The method name parameter can not be empty");
            }
            var methods = typeof(MultiOperationSmartContract).GetMethods().Where(x => x.Name == name && x.GetParameters().Length == parameters.Length);
            if (methods.Count() == 0) {
                throw new ArgumentException(string.Format("No method found with the name '{0}' and {1} parameters", name, parameters.Count()));
            }
            if (methods.Count() > 1) {
                throw new ArgumentException(string.Format("More than one method found with the name '{0}' and {1} parameters", name, parameters.Count()));
            }
            return methods.First().Invoke(null, parameters);
        }

        public static int Teste () => 1;

        public static int Teste1 (int v) => 2 + v;
        public static int Teste1 () => 2;

        public static void Hello(string a) => System.Console.WriteLine(a);
    }
}

MySmartContract.cs

namespace multi {
    using System;
    using System.Linq;
    public class MySmartContract : MultiEntryPointSmartContract {      
        public static int Teste () => 1;

        public static int Teste1 (int v) => 2 + v;
        public static int Teste1 () => 2;

        public static void Hello(string a) => System.Console.WriteLine(a);
    }
}