permutation column wise in matrix with random columns and row

class Program
   {
       static void Main(string[] args)
       {
           string[] set1 = { "AA0", "BC1", "XYZ", "000" };
           string[] set2 = { "AZ0", "BXY", "HIJ" };
           string[] set3 = { "A12", "BHO", "LMN" };

           ArrayList al = new ArrayList();
           al.Add(set1);
           al.Add(set2);
           al.Add(set3);



           List<List<string>> obj = new List<List<string>>();

           for (int i = 0; i < al.Count; i++)
           {

               for (int j = 0; j < 3; j++)
               {
                   List<string> allset = new List<string>();
                   var a = al.Cast<string[]>().ToList();
                   allset.AddRange(a[j]);
                   obj.Add(allset);
               }
           }

           //var itm = from d in obj select d[k].ToArray();
           //foreach (var item in itm)
           //{
           //    Console.WriteLine(item);
           //}
           for (int l = 0; l < obj.Count; l++)
           {
               for (int k = 0; k < 3; k++)
               {
                   //Console.WriteLine(obj[k]);
               }
           }
           int loopnumber = 1;

           ArrayList l2 = new ArrayList();
           for (int i = 0; i < obj.Count; i++)
           {



               for (int m = 0; m < obj[i].Count; m++)
               {
                   string str = "";
                   //condition_1: swap 3rd column of matrix
                   if (loopnumber == 1)
                   {
                       str += obj[i][0].ToString() + obj[i][1] + obj[m][2];

                   }
                   //condition_1: swap 3rd column of matrix
                   else if (loopnumber == 2)
                   {
                       //if (m == 0)
                       //{
                       //    i = 0;
                       //}

                       str += obj[i][0].ToString() + obj[m][1] + obj[i][2];

                   }
                   //condition_1: swap 3rd column of matrix
                   else if (loopnumber == 3)
                   {
                       //if (m == 0)
                       //{ i = 0; }

                       str += obj[m][0].ToString() + obj[i][1] + obj[i][2];
                   }
                   //if (l2.Contains(str) == false)
                   //{
                   l2.Add(str);
                   //}
               }
               //str += set1[i] + set1[i + 1] + set1[i + 2];
               //}
               if (i == 8)
               {
                   loopnumber++;
                   i = 0;
                   if (loopnumber > 3)
                   {
                       break;
                   }
               }
           }