FloodFillAlgorithm.java

package com.interview.graph;

/**
 * http://en.wikipedia.org/wiki/Flood_fill
 * 
 */
public class FloodFillAlgorithm {

    public void fillDFS(int screen[][], int oldColor, int newColor,int startx,int starty){
        fillUtil(screen,startx,starty,oldColor,newColor);
    }
    
    public void fillUtil(int screen[][], int currentx,int currenty, int oldColor, int newColor){
        if(currentx < 0 || currentx >= screen.length || currenty < 0 || currenty >= screen[currentx].length){
            return;
        }
        
        if(screen[currentx][currenty] != oldColor){
            return;
        }
        screen[currentx][currenty] = newColor;
        fillUtil(screen,currentx+1,currenty,oldColor,newColor);
        fillUtil(screen,currentx-1,currenty,oldColor,newColor);
        fillUtil(screen,currentx,currenty+1,oldColor,newColor);
        fillUtil(screen,currentx,currenty-1,oldColor,newColor);
    }
    
    public static void main(String args[]){
        int screen[][] = {{1,1,1,1,1,1},
                    {1,1,1,1,1,1},
                    {1,0,0,1,1,0},
                    {1,1,1,0,0,0},
                    {1,1,1,0,1,0},
                    {1,1,1,1,1,1}};
        FloodFillAlgorithm ff = new FloodFillAlgorithm();
        ff.fillDFS(screen, 0, 2, 3, 3);
        
        for(int i=0; i < screen.length; i++){
            for(int j=0; j < screen[i].length; j++){
                System.out.print(screen[i][j] + " ");
            }
            System.out.println();
        }
    }
}