Set Matrix Zeroes

/*
 * Problem : Process a matrix.
 * Input   : r and c, then r rows of c integers.
 * Output  : The new matrix.
 * Approach: Mark first, change later.
 * Time    : O(r * c)
 * Space   : O(r + c)
 * Java    : 8 or newer.
 */
import java.util.Scanner;

public class Main {
    // This method solves the task. It receives the input and returns the answer.
    static String[] solve(int[][] m) {
        int rows = m.length;
        int cols = m[0].length;

        // Step 1: First find all rows and columns that must become zero. We must not change the matrix yet.
        boolean[] zeroRow = new boolean[rows];
        boolean[] zeroCol = new boolean[cols];
        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                if (m[i][j] == 0) {
                    zeroRow[i] = true;
                    zeroCol[j] = true;
                }
            }
        }

        // Step 2: Now build the output. A cell is 0 if its row or its column is marked.
        String[] output = new String[rows];
        for (int i = 0; i < rows; i++) {
            StringBuilder row = new StringBuilder();
            for (int j = 0; j < cols; j++) {
                int value = zeroRow[i] || zeroCol[j] ? 0 : m[i][j];
                row.append(j == 0 ? "" : " ").append(value);
            }
            output[i] = row.toString();
        }
        return output;
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int rows = scanner.nextInt();
        int cols = scanner.nextInt();
        int[][] m = new int[rows][cols];
        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                m[i][j] = scanner.nextInt();
            }
        }
        System.out.println(String.join("\n", solve(m)));
    }
}