using System;

using System.Xml;

using System.Xml.Serialization;

using System.IO;

using System.Linq;

using System.Collections;

using System.Collections.Generic;

using System.Xml.Linq;

using System.Data;

using System.Collections.Specialized;

​

public class Program

{

    public static void Main()

    {

        NameValueCollection nvc = new NameValueCollection();

        nvc.Add("color", "red");

        nvc.Add("size", "s");

        nvc.Add("color", "red");

        nvc.Add("size", "m");

        nvc.Add("color", "red");

        nvc.Add("size", "l");

        //blue

        nvc.Add("color", "blue");

        nvc.Add("size", "m");

        nvc.Add("color", "blue");

        nvc.Add("size", "l");

        //green

        nvc.Add("color", "green");

        nvc.Add("size", "s");

        nvc.Add("color", "green");

        nvc.Add("size", "m");

        nvc.Add("color", "green");

        nvc.Add("size", "l");

​

        var results = nvc.AllKeys

                         .GroupBy(g=>g)

                         .Select(s=> 

                                 new 

                                 {

                                     key = s.Key,  

                                     values = nvc.GetValues(s.Key).Distinct() 

                                 }); 

        foreach(var result in results)

        {

            Console.WriteLine("{0}- {1}", result.key, string.Join(",", result.values) );

        }

​

​

    }

​

​

}

​

​

​

​

​

​