A brief analysis of .net strategy model

using System;
using ;
using ;
using ;
using ;
namespace DesignModel
{
    /// <summary>
/// Policy mode
    /// </summary>
    public class TacticsModel
    {
        public string type { get; set; }
        public virtual string GetResult()
        {
            return "";
        }
    }
    public class Normal:TacticsModel
    {
        public override string GetResult()
        {
return "normal price calculation";
        }
    }
    public class Discount : TacticsModel
    {
        public override string GetResult()
        {
return "Calculate price by discount";
        }
    }
    public class Preferential : TacticsModel
    {
        public override string GetResult()
        {
return "100 off activities for over 300";
        }
    }
    public class CashContext
    {
        TacticsModel tm = null;
        public CashContext(string type)
        {
            switch (type)
            {
                case "1":
                    tm = new Normal();
                    break;
                case "2":
                    tm = new Discount();
                    break;
                case "3":
                    tm = new Preferential();
                    break;
                default:
                break;
             }
        }
        public string GetResult()
        {
            return ();
        }
    }
}