排序含有數字的字符串：一個巧妙地方法

using System;using System.Collections.Generic; class PRogram{    static void Main(string[] args)    {        string[] floors ={ "第3樓", "第2樓", "第11樓" };        Array.Sort<string>(floors, Factory.Comparer);        foreach (string s in floors)            Console.WriteLine(s);        Console.ReadKey();    }} // 工廠模式class Factory : IComparer<string>{    private Factory() { }    public static IComparer<string> Comparer    {        get { return new Factory(); }    }    public int Compare(string x, string y)    {        return x.Length == y.Length ? x.CompareTo(y) : x.Length - y.Length;    }}