public class PublicClass
    {
        private string strReturn = string.Empty;
        private static int Count = 0;

        /// <summary>
        /// 组合算法
        /// </summary>
        /// <param name="s1">必选项</param>
        /// <param name="num">非必选项</param>
        /// <returns></returns>
        public string exec(string s1, string num)
        {
            string str = string.Empty;
            string[] spNum = num.Split(new char[] { ',' });
            str += showFirst(spNum);
            for (int i = 1; i <= spNum.Length; i++)
            {
                if (i != 1 && i != spNum.Length)
                {
                    split(num.Split(new char[] { ',' }), i);

                }

            }

            str += strReturn;
            str += num;
            return append(s1, str);
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="str">传入要组合的数组</param>
        /// <param name="numcount">分担的数量</param>
        private void split(string[] str, int numcount)
        {
            if (numcount < str.Length)
            {
                for (int i = 0; i < str.Length; i++)
                {
                    Down(str, str[i], numcount, i + 1);
                }

            }

        }

        private string showFirst(string[] num)
        {
            StringBuilder str = new StringBuilder();
            for (int i = 0; i < num.Length; i++)
            {
                if (!string.IsNullOrEmpty(num[i]))
                    str.AppendFormat("{0}|", num[i]);
            }
            return str.ToString();


        }

        /// <summary>
        /// 递归算法
        /// </summary>
        /// <param name="str">传入的要组合的数组</param>
        /// <param name="var">传入的拼接字符串</param>
        /// <param name="numcount">分担的数量</param>
        /// <param name="num">循环开始的大小</param>
        private void Down(string[] str, string var, int numcount, int num)
        {
            for (int i = num; i < str.Length; i++)
            {
                string Return = var + "," + str[i];
                if (numcount - i <= 1)//代表循环到最后一位i
                {
                    if (Return.Split(new char[] { ',' }).Length == numcount)
                        strReturn = strReturn + Return + "|";
                    else
                        Down(str, Return, numcount, i + 1);

                }
                else
                    Down(str, Return, numcount, i + 1);


            }


        }


        private string append(string s1, string append)
        {
            StringBuilder str = new StringBuilder();
            str.AppendFormat("0|", s1);
            Count = Count + 1;
            string[] split = append.Split(new char[] { ',' });
            for (int i = 0; i < split.Length; i++)
            {
                if (!string.IsNullOrEmpty(split[i]))
                {
                    Count = Count + 1;
                    str.AppendFormat("{0},{1}|", s1, split[i]);

                }


            }
            return str.ToString();

        }


        private int CountSum(string str)
        {
            int sumcount = 0;
            string[] s = str.Split(new char[] { ',' });
            foreach (string s1 in s)
            {
                if (!string.IsNullOrEmpty(s1))
                    sumcount = sumcount + 1;

            }

            return sumcount;

        }



    }