Help finding a bug in a C# program, arrays

Question

Programming

Problem statement: It is necessary to find the minimum element of the array (we will assume that it is the only one) and move the column with this element to the place of the first one;
Problem: 1) Finds the minimum incorrectly
2) Doesn't change the columns
PS sorry for the code, I'm just learning :)

int[,] A = new int[n, n];
            for (int i = 0; i < n; i++)
            {
                for (int j = 0; j < n; j++)
                    A[i, j] = Convert.ToInt32(dataGridView1.Rows[i].Cells[j].Value);
            }

            int min = A[0, 0], min_j = -1;
            for (int i = 0; i < n; i++)
            {
                for (int j = 0; j < n; j++)
                    if (min < A[i, j])
                    {
                        min = A[i, j];
                        min_j = j;
                    }
            }

            if (min_j != 0) ;
            {
                int rez;
                for (int i = 0; i < n; i++)
                {
                    rez = A[i, 0];
                    A[i, 0] = A[i, min_j];
                    A[i, min_j] = rez;
                    label1.Text = Convert.ToString(min);

                }
            }

Answer 1

In the IDE, you can press F9 for each line of code and see step by step where exactly the error has crept in. Plus, when you click on an error, the Error List will direct you to the desired line.
In the line if (min_j != 0) ; You need to remove the semicolon if I'm not mistaken.

Answer 2

You don't need a nested loop.
External do from 1 to n.
Make substitutions according to the algorithm:

rez = A[i, min_j];
A[i, min_j] = A[i, 0];
A[i, 0] = rez;

Answer 3

if (min < A[i, j])
Why less? If the minimum is less than some value, this is normal. To find the minimum, you still need (min > A[i, j])

int min = A[0, 0], min_j = -1;
...
 if (min_j != 0) ;

Also note that under some conditions (the minimum element was guessed right away), min_j will remain -1, which completely satisfies the min_j != 0 condition, but causes an exception. A more correct check looks faster.
And, as already mentioned above, the semicolon is completely superfluous.

Answer 4

Thank you very much! it remains to solve the problem by changing the columns, I tried to apply the following algorithm (carefully bydlokoda):

<code lang="cs">
            if (min_j > 0)
            {
                int rez;
                for (int i = 0; i > -1; i--)
                {
                    for (int j = min_j; j > -1; j--)
                    {
                            rez = A[i, j];
                            A[i, j] = A[i, j + 1];
                            A[i, j + 1] = rez;
                    }

                }

            }

</code>

I changed it a bit from the one above, since the shift should be cyclical, but all the same my attempts are unsuccessful.

Answer 5

if(min_j > 0)
{
   int rez;
   for(i = 0; i<n; i++)
   {
     rez = A[i, min_j];
     A[i, min_j] = A[i, 0];
     A[i, 0] = rez;
   }
}