Question

I’m trying to apply the flood fill on a specific question. I’m having a hard time understanding how to create a variable with a help function so I keep it throughout all the recursion.
I’ve seen there is a thread about it though I don’t know how to apply it for my own use.

This is the code I wrote so far:

how do I create the k variable to stay the same?

public static int[][] fill(int[][] map, int i, int j, int color) {
    int[][] ans = null;

    if ((i<map.length)&&(i>0)&&(j<map.length)&&(j>0))
    {
        if ((k!=map[i][j]))
        {
            map[i][j]=color;    
        }
    }
    fill(map,i-1,j,color);
    fill(map,i+1,j,color);
    fill(map,i,j-1,color);
    fill(map,i,j+1,color);
    return ans;
}

public static void fill(int[][] map, int i, int j, int color,int k)

k=map[i][j] 

lets say this is my array:

4, 1, 2, 2
4, 4, 3, 1
1, 4, 4, 4

1, 4, 0, 2

and I wish to flood fill all the indexes that have the value of 4.
I wish k to obtain the value of 4 so I can use k to compare in each index.

Answer 1

Iמ Addition to your question i have noticed that your function wont work because you boundries checking, you are check if row or col are equal to the board length , its alright but you need to change it to <, and not <= . anyway you can use your code like that :

public static int[][] fill(int[][] map, int i, int j, int color) {

    int origColor = map[i][j];
    fill(map, i, j, color, origColor);


    return map;

    }

private static void fill(int[][] map, int i, int j,int color, int   origColor) {



    //checks if index is inside matrix and if the index is equal to original   number.

    if ((i<map.length)&&(i>=0)&&(j<map.length)&&(j>=0)&&(origColor==map[i][j]))

    {

    map[i][j]=color;



    //recursive call for north east west south.

    fill(map,i-1,j,color,origColor);

    fill(map,i+1,j,color,origColor);

    fill(map,i,j-1,color,origColor);

    fill(map,i,j+1,color,origColor);
    }


    }
 public static void printBoard(int[][] board) {
if (board == null)
    System.out.println("null");
else for (int i=0; i<board.length; i++) {
    if (board[i] == null)
        System.out.println("null");
    else
        for (int j=0; j<board[i].length; j++) 
            System.out.print(board[i][j]);
    System.out.println();
}
}

for checking :

fill(map,1,1,9);
    printBoard(map);

Good Luck!