CountCells.java

package Recursion;

public class CountCells {
    public static final int N = 8;
    public static int grid[][] = {
            { 1, 0, 0, 0, 0, 0, 0, 1 },
            { 0, 1, 1, 0, 0, 1, 0, 0 },
            { 1, 1, 0, 0, 1, 0, 1, 0 },
            { 0, 0, 0, 0, 0, 1, 0, 0 },
            { 0, 1, 0, 1, 0, 1, 0, 0 },
            { 0, 1, 0, 1, 0, 1, 0, 0 },
            { 1, 0, 0, 0, 1, 0, 0, 1 },
            { 0, 1, 1, 0, 0, 1, 1, 1 }
    };

    // private static int BACKGROUND_COLOR = 0; //not used
    private static int IMAGE_COLOR = 1;
    private static int ALREADY_COUNTED = 2;

    public int countCellsInBlob(int x, int y) {
        if (x < 0 || y < 0 || x >= N || y >= N)
            return 0;
        else if (grid[x][y] != IMAGE_COLOR)
            return 0;
        else {
            grid[x][y] = ALREADY_COUNTED;
            return 1 + countCellsInBlob(x - 1, y + 1) + countCellsInBlob(x, y + 1) + countCellsInBlob(x + 1, y + 1)
                    + countCellsInBlob(x - 1, y) + countCellsInBlob(x + 1, y)
                    + countCellsInBlob(x - 1, y - 1) + countCellsInBlob(x, y - 1) + countCellsInBlob(x + 1, y - 1);
        }
    }

    public static void printGrid() {
        for (int i = 0; i < N; i++) {
            for (int j = 0; j < N; j++) {
                System.out.print(grid[i][j] + " ");
            }
            System.out.println();
        }
    }

    public static void main(String[] args) {
        CountCells cc = new CountCells();
        System.out.println("before counting");
        printGrid();

        System.out.println("blob size : " + cc.countCellsInBlob(3, 5));

        System.out.println("after counting");
        printGrid();
    }
}