Fill Matrix

using System;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            string type = Console.ReadLine();

            int[,] matrix = new int[n, n];

            if (type == "a")
            {
                FillMatrixCaseA(matrix, n);
            }
            else if (type == "b")
            {
                FillMatrixCaseB(matrix, n);
            }
            else if (type == "c")
            {
                FillMatrixCaseC(matrix, n);
            }
            else if (type == "d")
            {
                FillMatrixCaseD(matrix, n);
            }

            PrintMatrix(matrix);
        }

        private static void PrintMatrix(int[,] matrix)
        {
            for (int i = 0; i < matrix.GetLength(0); i++)
            {
                for (int j = 0; j < matrix.GetLength(0); j++)
                {
                    Console.Write(matrix[i,j] + " ");
                }
                Console.WriteLine();
            }
        }

        private static void FillMatrixCaseD(int[,] matrix, int n)
        {
            int step = 1;
            int row = 0;
            int column = 0;

            while (row < matrix.GetLength(0))
            {
                matrix[row, column] = step;
                row++;
                step++;
            }
            row--;
            column++;
            while (column < matrix.GetLength(1))
            {
                matrix[row, column] = step;
                column++;
                step++;
            }
            row--;
            column--;
            while (row >= 0)
            {
                matrix[row, column] = step;
                step++;
                row--;
            }
            column--;
            row++;
            while (column >= 1)
            {
                matrix[row, column] = step;
                step++;
                column--;
            }
            column++;
            row++;

            while (step <= matrix.Length)
            {
                while (matrix[row, column] == 0)
                {
                    matrix[row, column] = step;
                    row++;
                    step++;
                }
                if (step > matrix.Length)
                {
                    break;
                }
                row--;
                column++;
                while (matrix[row, column] == 0)
                {
                    matrix[row, column] = step;
                    column++;
                    step++;
                }
                if (step > matrix.Length)
                {
                    break;
                }
                row--;
                column--;
                while (matrix[row, column] == 0)
                {
                    matrix[row, column] = step;
                    step++;
                    row--;
                }
                if (step > matrix.Length)
                {
                    break;
                }
                column--;
                row++;
                while (matrix[row, column] == 0)
                {
                    matrix[row, column] = step;
                    step++;
                    column--;
                }
                if (step > matrix.Length)
                {
                    break;
                }
                column++;
                row++;
            }


        }

        private static void FillMatrixCaseC(int[,] matrix, int n)
        {
            int row = n - 1;
            int col = 0;
            int count = 1;
            int num = 1;
            for (int i = n - 1; i >= 0; i--)
            {
                for (int j = 0; j < count; j++)
                {
                    matrix[row, col] = num;
                    row++;
                    col++;
                    num++;
                }
                row = i - 1;
                col = 0;
                count++;
            }
            row = 0;
            count = 0;
            for (int i = 0; i < n - 1; i++)
            {
                col = i + 1;
                for (int j = count; j < n - 1; j++)
                {
                    matrix[row, col] = num;
                    num++;
                    row++;
                    col++;
                }
                row = 0;
                count++;
            }
        }

        private static void FillMatrixCaseB(int[,] matrix, int n)
        {
            int count = 1;
            int row = 0;
            while (count <= n * n)
            {
                for (int i = row; i < row + 1; i++)
                {
                    for (int j = 0; j < n; j++)
                    {
                        matrix[j, i] = count;
                        count++;
                    }
                }
                row++;
                if (count >= n * n)
                {
                    break;
                }
                for (int i = row; i < row + 1; i++)
                {
                    for (int j = n - 1; j >= 0; j--)
                    {
                        matrix[j, i] = count;
                        count++;
                    }
                }
                row++;
            }
        }

        private static void FillMatrixCaseA(int[,] matrix, int n)
        {
            int num = 1;
            for (int i = 0; i < n; i++)
            {
                for (int j = 0; j < n; j++)
                {
                    matrix[j, i] = num;
                    num++;
                }
            }
        }
    }
}