求排列 组合 函数！
有一个list<T> 里面有N个数,比如 1 ，2 ，3 ， 4

我想写一个函数 函数参数是(list<T> lst, int pic)

lst 是上面那个list pic如果为2

想返回 1,2 1,3 1,4 2,3 2,4 3,4

哪个高手能写一个通用的方法呢？ 在线等~！


[解决办法]

C# code

static void Main(string[] args)        {            string[] Sample = new string[] { "0", "1", "2", "3", "4", "5","6","7","8","9","a","b","c","d","e","f","g" };            List<string> SampleList = new List<string>();            SampleList.AddRange(Sample);            List<string> result = getCombination(SampleList, 3);            Console.Read();        }        static List<string> getCombination(List<string> SampleList, int m)        {            if (m == 1)            {                return SampleList;            }            List<string> result = new List<string>();            if (SampleList.Count == m)            {                StringBuilder temp_sb = new StringBuilder();                foreach (string s in SampleList)                {                    temp_sb.Append(s);                }                result.Add(temp_sb.ToString());                Console.WriteLine(temp_sb.ToString());                return result;            }            string temp_firstelement = SampleList[0];            SampleList.RemoveAt(0);            List<string> temp_samplist1 = new List<string>();            temp_samplist1.AddRange(SampleList);            List<string> temp_list1 = getCombination(temp_samplist1, m - 1);            foreach (string s in temp_list1)            {                result.Add(temp_firstelement + s);                Console.WriteLine(temp_firstelement + s);            }                    List<string> temp_samplist2 = new List<string>();            temp_samplist2.AddRange(SampleList);            List<string> temp_list2 = getCombination(temp_samplist2, m);            result.AddRange(temp_list2);                        return result;        }    }}
[解决办法]
int[] data = { 1, 2, 3, 4 };
var query = from a in data
           from b in data
           select a.ToString() + "," + b.ToString();
foreach (var item in query)
{
   Console.WriteLine(item);
}
[解决办法]
http://www.cnblogs.com/rogerwei/archive/2010/11/18/1880336.html
[解决办法]
写一个通用的：
IEnumerable<IEnumerable<T>> Combo<T>(IEnumerable<<IEnumerable<T>> source, IEnumerable<T> data)
{
   return data.SelectManay(x => source.Select(y => y.Concat(new T[] { x })));
}
[解决办法]
C# code
        int[] data = { 1, 2, 3, 4 };        private void SetData(int start,int count)        {            if (start == count - 1) return;            for (int i = start+1; i < count; i++)            {                Debug.WriteLine(data[start].ToString() + "," + data[i].ToString());                listBox1.Items.Add(data[start].ToString() + "," + data[i].ToString());                            }            SetImage(start + 1, data.Length);        }使用SetData(0, data.Length);/*1,21,31,42,32,43,4*/