Flood-Fill

// http://www.geeksforgeeks.org/flood-fill-algorithm-implement-fill-paint/
public class FloodFill0 {
    // Driver program to test above function
    public static void main(String[] args) {
        int[][] screen = {
                { 1, 1, 1, 1, 1, 1, 1, 1 },
                { 1, 1, 1, 1, 1, 1, 0, 0 },
                { 1, 0, 0, 1, 1, 0, 1, 1 },
                { 1, 2, 2, 2, 2, 0, 1, 0 },
                { 1, 1, 1, 2, 2, 0, 1, 0 },
                { 1, 1, 1, 2, 2, 2, 2, 0 },
                { 1, 1, 1, 1, 1, 2, 1, 1 },
                { 1, 1, 1, 1, 1, 2, 2, 1 }
        };

        int x = 4, y = 4, newC = 3;

        floodFill(screen, x, y, newC);
        printr(screen);
    }

    // A recursive function to replace previous color 'prevC' at '(x, y)'
    // and all surrounding pixels of (x, y) with new color 'newC' and
    private static void floodFillUtil(int arr[][], int x, int y, int prevC, int newC) {
        // Base cases
        if (x < 0 || x >= arr[0].length || y < 0 || y >= arr.length) return;
        if (arr[x][y] != prevC) return;

        // Replace the color at (x, y)
        arr[x][y] = newC;

        // Recur for north, east, south and west
        floodFillUtil(arr, x + 1, y, prevC, newC);
        floodFillUtil(arr, x - 1, y, prevC, newC);
        floodFillUtil(arr, x, y + 1, prevC, newC);
        floodFillUtil(arr, x, y - 1, prevC, newC);
    }

    // It mainly finds the previous color on (x, y) and calls floodFillUtil()
    public static void floodFill(int screen[][], int x, int y, int newC) {
        int prevC = screen[x][y];
        floodFillUtil(screen, x, y, prevC, newC);
    }

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

// =================================================================

// http://www.geeksforgeeks.org/flood-fill-algorithm-implement-fill-paint/
public class FloodFill1 {
    // Driver program to test above function
    public static void main(String[] args) {
        int[][] screen = {
                { 1, 1, 1, 1, 1, 1, 1, 1 },
                { 1, 1, 1, 1, 1, 1, 0, 0 },
                { 1, 0, 0, 1, 1, 0, 1, 1 },
                { 1, 2, 2, 2, 2, 0, 1, 0 },
                { 1, 1, 1, 2, 2, 0, 1, 0 },
                { 1, 1, 1, 2, 2, 2, 2, 0 },
                { 1, 1, 1, 1, 1, 2, 1, 1 },
                { 1, 1, 1, 1, 1, 2, 2, 1 }
        };

        int x = 4, y = 4, newC = 3;

        floodFill(screen, x, y, newC);
        printr(screen);
    }

    // A recursive function to replace previous color 'prevC' at '(x, y)'
    // and all surrounding pixels of (x, y) with new color 'newC' and
    private static void floodFillUtil(int arr[][], int x, int y, int prevC, int newC) {
        // Base cases
        if (!inBounds(arr, x, y)) return;
        if (arr[x][y] != prevC) return;

        // Replace the color at (x, y)
        arr[x][y] = newC;

        // Recur for north, east, south and west
        floodFillUtil(arr, x + 1, y, prevC, newC);
        floodFillUtil(arr, x - 1, y, prevC, newC);
        floodFillUtil(arr, x, y + 1, prevC, newC);
        floodFillUtil(arr, x, y - 1, prevC, newC);
    }

    // It mainly finds the previous color on (x, y) and calls floodFillUtil()
    public static void floodFill(int screen[][], int x, int y, int newC) {
        int prevC = screen[x][y];
        floodFillUtil(screen, x, y, prevC, newC);
    }

    private static boolean inBounds(int[][] arr, int x, int y) {
        return x >= 0 && x < arr[0].length && y >= 0 && y < arr.length;
    }

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

// =================================================================

public class FloodFill2 {
    public static void main(String[] args) {
        Integer[][] screen = {
                { 1, 1, 1, 1, 1, 1, 1, 1 },
                { 1, 1, 1, 1, 1, 1, 0, 0 },
                { 1, 0, 0, 1, 1, 0, 1, 1 },
                { 1, 2, 2, 2, 2, 0, 1, 0 },
                { 1, 1, 1, 2, 2, 0, 1, 0 },
                { 1, 1, 1, 2, 2, 2, 2, 0 },
                { 1, 1, 1, 1, 1, 2, 1, 1 },
                { 1, 1, 1, 1, 1, 2, 2, 1 }
        };

        floodFill(screen, 4, 4, 3);
        print(screen);
    }


    public static <T> void floodFill(T arr[][], int x, int y, T curr) {
        floodFillUtil(arr, x, y, arr[x][y], curr);
    }

    private static <T> void floodFillUtil(T arr[][], int x, int y, T prev, T curr) {
        // Base cases
        if (!inBounds(arr, x, y)) return;
        if (!arr[x][y].equals(prev)) return;

        // Replace the color at (x, y)
        arr[x][y] = curr;

        // Recur for north, east, south and west
        floodFillUtil(arr, x + 1, y, prev, curr);
        floodFillUtil(arr, x - 1, y, prev, curr);
        floodFillUtil(arr, x, y + 1, prev, curr);
        floodFillUtil(arr, x, y - 1, prev, curr);
    }

    private static <T> boolean inBounds(T[][] arr, int x, int y) {
        return x >= 0 && x < arr[0].length && y >= 0 && y < arr.length;
    }

    public static <T> String sprint(T[][] arr) {
        return join(new StringBuffer(), arr, " ").toString();
    }

    public static <T> StringBuffer join(StringBuffer buffer, T[][] arr, String delim) {
        for (T[] row : arr) {
            join(buffer, row, delim).append(System.lineSeparator());
        }
        return buffer;
    }

    public static <T> StringBuffer join(StringBuffer buffer, T[] arr, String delim) {
        for (int i = 0; i < arr.length; i++) {
            buffer.append(arr[i]);
            if (i < arr.length - 1) {
                buffer.append(delim);
            }
        }
        return buffer;
    }

    public static <T> void print(T[][] arr) {
        System.out.println(sprint(arr));
    }
}