Question9_7.java

/**
 * Implement the "paint fill" function that one might see on many image editing programs.
 * That is, given a screen (represented by a two-dimensional array of colors), a point, and a new color,
 * fill in the surrounding area until the color changes from the original color.
 *  
 * Time  Complexity: O(mn)
 * Space Complexity: O(mn)
 */

public class Question9_7 {
    public void paintFill(char[][] screen, int x, int y, char newColor) {
        if (screen == null || screen.length == 0 || screen[0].length == 0) {
            return;
        }
        
        int height = screen.length;
        int width = screen[0].length;
        
        if (x < 0 || x >= width || y < 0 || y >= height) {
            return;
        }
        
        if (screen[y][x] != newColor) {
            screen[y][x] = newColor;
            paintFill(screen, x - 1, y, newColor);
            paintFill(screen, x + 1, y, newColor);
            paintFill(screen, x, y - 1, newColor);
            paintFill(screen, x, y + 1, newColor);
        }
        
        return;
    }
}