FloodFill.java

package com.thealgorithms.backtracking;

/**
 * Java program for Flood fill algorithm.
 * @author Akshay Dubey (https://github.com/itsAkshayDubey)
 */
public class FloodFill {

    /**
     * Get the color at the given co-odrinates of a 2D image
     *
     * @param image The image to be filled
     * @param x The x co-ordinate of which color is to be obtained
     * @param y The y co-ordinate of which color is to be obtained
     */
	
	public static int getPixel(int[][] image, int x, int y) {
	
		return image[x][y];
	
	}
	
    /**
     * Put the color at the given co-odrinates of a 2D image
     *
     * @param image The image to be filed
     * @param x The x co-ordinate at which color is to be filled
     * @param y The y co-ordinate at which color is to be filled
     */
	public static void putPixel(int[][] image, int x, int y, int newColor) {
		
		image[x][y] = newColor;
	
	}
	
	
    /**
     * Fill the 2D image with new color
     *
     * @param image The image to be filed
     * @param x The x co-ordinate at which color is to be filled
     * @param y The y co-ordinate at which color is to be filled
     * @param newColor The new color which to be filled in the image
     * @param oldColor The old color which is to be replaced in the image
     * @return
     */
	public static void floodFill(int[][] image, int x, int y, int newColor, int oldColor) {

		if(x < 0 || x >= image.length) return;
		if(y < 0 || y >= image[x].length) return;
		if(getPixel(image, x, y) != oldColor) return;

		putPixel(image, x, y, newColor);

		/* Recursively check for horizontally & vertically adjacent coordinates */
		floodFill(image, x + 1, y, newColor, oldColor);
		floodFill(image, x - 1, y, newColor, oldColor);
		floodFill(image, x, y + 1, newColor, oldColor);
		floodFill(image, x, y - 1, newColor, oldColor);

		/* Recursively check for diagonally adjacent coordinates  */
		floodFill(image, x + 1, y - 1, newColor, oldColor);
		floodFill(image, x - 1, y + 1, newColor, oldColor);
		floodFill(image, x + 1, y + 1, newColor, oldColor);
		floodFill(image, x - 1, y - 1, newColor, oldColor);

	}

}