FillTheMatrix

using System;
class FillTheMatrix
{
    static void Main()
    {
        int rowsAndColsSize = int.Parse(Console.ReadLine());
        char pattern = (char)Console.Read();

        int[,] matrix = new int[rowsAndColsSize, rowsAndColsSize];
        int currentNumber = 1;
        if (Char.ToUpper(pattern).Equals('A'))
        {
            for (int col = 0; col < rowsAndColsSize; col++)
            {
                for (int row = 0; row < rowsAndColsSize; row++)
                {
                    matrix[row, col] = currentNumber;
                    currentNumber++;
                }
            }
        }
        else if (Char.ToUpper(pattern).Equals('B'))
        {
            for (int col = 0; col < rowsAndColsSize; col++)
            {
                if (col % 2 == 0)
                {
                    for (int row = 0; row < rowsAndColsSize; row++)
                    {
                        matrix[row, col] = currentNumber;
                        currentNumber++;
                    }
                }
                else
                {
                    for (int row = rowsAndColsSize - 1; row >= 0; row--)
                    {
                        matrix[row, col] = currentNumber;
                        currentNumber++;
                    }
                }
            }
        }

        for (int row = 0; row < rowsAndColsSize; row++)
        {
            for (int col = 0; col < rowsAndColsSize; col++)
            {
                Console.Write("{0,2} ", matrix[row, col]);
            }
            Console.WriteLine();
        }
    }
}