12. The Matrix - Stack!!!

import java.util.ArrayDeque;
import java.util.Scanner;

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

        int r = scanner.nextInt();
        int c = scanner.nextInt();
        scanner.nextLine();

        char[][] matrix = new char[r][c];

        for (int i = 0; i < r; i++) {
            matrix[i] = scanner.nextLine().replaceAll(" ", "").toCharArray();
        }

        char fillChar = scanner.nextLine().charAt(0);

        int fillRow = scanner.nextInt();
        int fillCol = scanner.nextInt();

        char toBeReplaced = matrix[fillRow][fillCol];

        ArrayDeque<int[]> stack = new ArrayDeque<>();

        stack.push(new int[]{fillRow, fillCol});

        while (!stack.isEmpty()) {
            int[] indexes = stack.pop();
            int row = indexes[0];
            int col = indexes[1];
            matrix[row][col] = fillChar;
            if (isInBounds(matrix, row + 1, col) && matrix[row + 1][col] == toBeReplaced) {
                stack.push(new int[]{row + 1, col});
            }
            if (isInBounds(matrix, row - 1, col) && matrix[row - 1][col] == toBeReplaced) {
                stack.push(new int[]{row - 1, col});
            }
            if (isInBounds(matrix, row, col + 1) && matrix[row][col + 1] == toBeReplaced) {
                stack.push(new int[]{row, col + 1});
            }
            if (isInBounds(matrix, row, col - 1) && matrix[row][col - 1] == toBeReplaced) {
                stack.push(new int[]{row, col - 1});
            }
        }

        //paintMatrix(matrix, toBeReplaced, fillChar, fillRow, fillCol);

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

    }

    private static void paintMatrix(char[][] matrix, char toBeReplaced, char fillChar, int fillRow, int fillCol) {
        if (!isInBounds(matrix, fillRow, fillCol) || matrix[fillRow][fillCol] != toBeReplaced) {
            return;
        }

        matrix[fillRow][fillCol] = fillChar;

        paintMatrix(matrix, toBeReplaced, fillChar, fillRow - 1, fillCol);
        paintMatrix(matrix, toBeReplaced, fillChar, fillRow + 1, fillCol);
        paintMatrix(matrix, toBeReplaced, fillChar, fillRow, fillCol - 1);
        paintMatrix(matrix, toBeReplaced, fillChar, fillRow, fillCol + 1);

    }

    private static boolean isInBounds(char[][] matrix, int fillRow, int fillCol) {
        return  fillRow >= 0 && fillRow < matrix.length && fillCol >= 0 && fillCol < matrix[fillRow].length;
    }

}