gistfile1.cs

using System;
using System.Text.RegularExpressions;

namespace CVS_Ver
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(MaxVer(new string[] { "1.1", "1.2", "1.3", "1.3.2.1", "1.3.2.3", "1.3.2.4", "1.3.2.5.1", "1.3.4.1", "1.4", "1.5" }, "1.3.0.2"));
        }

        static string MaxVer(string[] FileVersions, string BaseVersion)
        {
            string Version = Regex.Replace(BaseVersion,@"(.*)\.0(\.\d+)","$1$2.");
            string MaxVersion = Version;
            for (int i = 0; i < FileVersions.Length; i++)
                if (FileVersions[i].StartsWith(Version) &&
                    FileVersions[i].Trim().Length==Version.Length+1 &&//don't search in inner branches
                    String.Compare(FileVersions[i], MaxVersion) == 1)
                    MaxVersion = FileVersions[i];
            return MaxVersion;
        }
    }
}