1.Fill the Matrix

import java.util.Scanner;

public class matrix1_Exercises_1Fill_The_Matrix {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        String[] input = scanner.nextLine().split(", ");


        int row = Integer.parseInt(input[0]);
        int[][] matrix = new int[row][row];
        int count = 0;
        int r = 0;
        int c = 0;
        boolean flag = true;
        if (input[1].equals("A")) {
            while (count++ < row * row) {

                matrix[r][c] = count;
                if (matrix[r][c] == row * row) {
                    break;
                }
                if (r == row - 1) {
                    c++;
                    r = -1;
                }
                r++;


            }
        } else if (input[1].equals("B")) {
            while (count++ < row * row) {

                matrix[r][c] = count;
                if (matrix[r][c] == row * row) {
                    break;
                }
                if (r == row - 1 && flag) {
                    c++;
                    flag = false;
                    r++;
                }
                if (r == 0 && !flag) {
                    c++;
                    flag = true;
                    r--;
                }
                if (!flag) {
                    r--;
                } else {
                    r++;
                }

            }
        }

        for (int i = 0; i < row; i++) {
            for (int j = 0; j < row; j++) {
                System.out.print(matrix[i][j] + " ");
            }
            System.out.println();
        }

    }

}