11. Reverse Matrix Diagonals

package Uprajnenie;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;

public class ReverseMatrixDiagonals {
        public static void main(String[] args) throws IOException {


            BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

            int[] dimensions = Arrays.stream(reader.readLine().trim().split("\\s+")).mapToInt(Integer::parseInt).toArray();
            int rows = dimensions[0];
            int cols = dimensions[1];

            int[][] matrix = new int[rows][cols];

            for (int row = 0; row < rows; row++) {
                matrix[row] = Arrays.stream(reader.readLine().trim().split("\\s+")).mapToInt(Integer::parseInt).toArray();
            }

            StringBuilder sb = new StringBuilder();

            for (int diagonal = cols - 1; diagonal >= 0; diagonal--) {
                int row = rows - 1;
                int col = diagonal;

                while (row >= 0 && col < cols) {
                    sb.append(matrix[row--][col++]).append(' ');
                }
                sb.append(System.lineSeparator());
            }

            for (int startRow = rows - 2; startRow >= 0; startRow--) {
                int row = startRow;
                int col = 0;

                while (row >= 0 && col < cols) {
                    sb.append(matrix[row--][col++]).append(' ');
                }
                sb.append(System.lineSeparator());
            }

            System.out.println(sb.toString().trim());
        }
    }