Question

I’m working on a program to generate random grids, latin squares, and sudoku. I am working on the latin squares and pretty much have it all working except I am in a continuous loop. If I break them up they work fine. There is probably something small I am doing wrong and I can’t find it. Can you spot what’s wrong?

EDIT: For those that don’t know what Latin Square is (if someone doesn’t know) its usually a 9×9 grid that doesn’t have repeats in either rows nor columns.

UPDATE: I found a problem with the notSame equaling true right before if(notSame) statement. It was always equaling true so wouldn’t finish checking the row. Now when I run it is no longer in continuous loop but instead the rows have no repeats but columns still do.

UPDATE #2: I now redid a lot of the coding for the columns. My professor asked me to change a few things but it still puts me in to a continuous loop.

int row = 0, col = 0, count = 0;
bool notSame = true;
// setting up rows and columns
for (row = 0; row < grid.GetLength(0); row++)
{
   for (col = 0; col < grid.GetLength(1); col++)
   {

       grid[row, col] = rnd.Next(1, 10);

       //for loop to check rows for repeats
       for (int c = 0; c < col; c++)
       {
           // if there is repeat go back a column and set bool = false
           if (grid[row, col] == grid[row, c])
           {
               col--;
               count++;
               notSame = false;
               break;
            }

            //notSame = true;
        }

     // if bool = true loop to check columns for repeats
     if (notSame)
     {

         for (int r = 0; r < row; r++)
         {
         // if repeat then go back row
            if (grid[row, col] == grid[r, col])
            {
                notSame = false;
                count++;
                break;
             }

          }
          if (notSame == false && count <= 50)
          {
               row--;
               //break;
          }
          else if (notSame == false && count > 50)
          {
               count = 0;
               col = 0;
               row = 0;
               break;
          }
      }
   }
}

I am using a 2D array called grid.

Answer 1

My problem was an extra count in the check for rows. The count would always go over 50 and therefore would cause an infinite loop. To clarify:

grid[row, col] = rnd.Next(1, 10);

   //for loop to check rows for repeats
   for (int c = 0; c < col; c++)
   {
       // if there is repeat go back a column and set bool = false
       if (grid[row, col] == grid[row, c])
       {
           col--;
           count++;
           notSame = false;
           break;
        }

        //notSame = true;
    }

The count++ would increment and would at times end up > = 50 which would then kick in this code:

 else if (notSame == false && count > 50)
      {
           count = 0;
           col = 0;
           row = 0;
           break;
      }

Which then cause everything to be set back to 0 and would restart. Therefore, it caused an infinite loop. Thanks all for the help!