{
{"1","aaa"},
{"1","bbb"},
{"2","ccc"},
{"2","ddd"},
{"3","uuu"},
{"1","eee"},
{"4","aaa"},
{"4","qqq"}
}

        string[,] values = { { "1", "aaa" }, { "1", "bbb" }, { "2", "ccc" }, { "2", "ddd" }, { "3", "uuu" }, { "1", "eee" }, { "4", "aaa" }, { "4", "qqq" } };
        SortedList<string, string> sortedList = new SortedList<string, string>();
        for (int i = 0; i < values.GetLength(0); i++)
        {
            if (sortedList.ContainsKey(values[i, 0]))
                sortedList[values[i, 0]] += "," + values[i, 1];
            else
                sortedList.Add(values[i, 0], values[i, 1]);
        }
        for (int i = 0; i < sortedList.Count; i++)
            if (!sortedList[sortedList.Keys[i]].Contains(','))
                sortedList.RemoveAt(i--);
        if (sortedList.Count > 1)
        {
            for (int i = 0; i < sortedList.Count; i++)
            {
                for (int j = i + 1; j < sortedList.Count; j++)
                {
                    string[] values1 = sortedList[sortedList.Keys[i]].Split(',');
                    string[] values2 = sortedList[sortedList.Keys[j]].Split(',');
                    if (values1.Intersect(values2).Count() > 0)
                    {
                        sortedList[sortedList.Keys[i]] = string.Join(",", values1.Union(values2).ToArray());
                        sortedList.RemoveAt(j--);
                    }
                }
            }
        }
        foreach (KeyValuePair<string, string> pair in sortedList)
            Console.WriteLine(pair.Value);

------解决方案--------------------
C# code
namespace SumString
{
    class Program
    {
       static string[,] str = new string[,] { { "1", "aaa" }, { "1", "bbb" }, { "2", "ccc" }, { "2", "ddd" }, 
                                                { "3", "uuu" }, { "1", "eee" }, { "4", "aaa" }, { "4", "qqq" } };
       static List<string[,]> list = new List<string[,]>();
       static List<string> listid = new List<string>();
        
        static void Main(string[] args)
        {
            Addlist();
            foreach (string[,] str in list)
            {
                if (!listid.Contains(str[0, 0]))
                {
                    if(SumString(str).TrimEnd(new char[]{','}).Contains(","))
                    Console.WriteLine("{0}--{1}", str[0, 0], SumString(str).TrimEnd(new char[]{','}));
                }
                listid.Add(str[0,0]);
                              
            }
            Console.ReadKey();
            
        }
         public static string SumString(string [,] para)
        {
            string str="";
            foreach (string[,] s in list)
            {
                if (s[0, 0] == para[0,0])
                {
                    str += s[0, 1] + ",";
                }
            }
            return str;
        }
        public static void Addlist( )