using System;

using System.Linq;

using System.Diagnostics;

using System.Collections.Generic;

using System.Text;

public class Program

{

    static Random R = new Random();

​

    public static void Main(string[] args)

    {

        var testSuite = GenerateTests(10);

​

        Benchmark(Diego, testSuite);

        Benchmark(Fran, testSuite);

    }

​

    static int Diego(string strTest)

    {

        return 477 - strTest.Select(c => (int)c).Sum();

    }

​

    static int Fran(string numStr)

    {

        int asciiSum = 0;

        foreach(char c in numStr){

            asciiSum += '9'-c;  

        }

        return (asciiSum+4)%10;

    }

​

    #region Benchmark

        delegate int DlgTest(string s);

​

    private static void Benchmark(DlgTest func, List<string> testSuite)

    {

        Stopwatch sw = Stopwatch.StartNew();

        foreach (var str in testSuite)

            func.Invoke(str);

        sw.Stop();

        Console.WriteLine((sw.ElapsedTicks).ToString());

    }

​

    static List<string> GenerateTests(int nTests)

    {

        var RetVal = new List<string>();

        while (RetVal.Count < nTests)

        {

            RetVal.Add(GenerateTest());

        }

        return RetVal;

    }

​

    static string GenerateTest()

    {

        var sb = new StringBuilder();

        var auxStr = "0123456789";

​

        for (var i = 1; i <= 9; i++)

        {

            var rnd = GenerateRandom(auxStr.Length - 1);

            sb.Append(auxStr[rnd]);

            auxStr = auxStr.Remove(rnd, 1);

        }

​

        return sb.ToString();

    }

​

    static int GenerateRandom(int max)

    {

        return R.Next(max + 1);

    }

    #endregion    

}

​