In this post, we are going to solve the 733. Flood Fill problem of Leetcode. This problem 733. Flood Fill is a Leetcode easy level problem. Let’s see the code, 733. Flood Fill – Leetcode Solution.

Problem

An image is represented by an m x n integer grid image where image[i][j] represents the pixel value of the image.

You are also given three integers sr, sc, and color. You should perform a flood fill on the image starting from the pixel image[sr][sc].

To perform a flood fill, consider the starting pixel, plus any pixels connected 4-directionally to the starting pixel of the same color as the starting pixel, plus any pixels connected 4-directionally to those pixels (also with the same color), and so on. Replace the color of all of the aforementioned pixels with color.

Return the modified image after performing the flood fill.

Example 1 :

Input: image = [[1,1,1],[1,1,0],[1,0,1]], sr = 1, sc = 1, color = 2
Output: [[2,2,2],[2,2,0],[2,0,1]]
Explanation: From the center of the image with position (sr, sc) = (1, 1) (i.e., the red pixel), all pixels connected by a path of the same color as the starting pixel (i.e., the blue pixels) are colored with the new color.
Note the bottom corner is not colored 2, because it is not 4-directionally connected to the starting pixel.

Example 2 :

Input: image = [[0,0,0],[0,0,0]], sr = 0, sc = 0, color = 0
Output: [[0,0,0],[0,0,0]]
Explanation: The starting pixel is already colored 0, so no changes are made to the image.

Constraints

• m == image.length
• n == image[i].length
• 1 <= m, n <= 50
• 0 <= image[i][j], color < 216
• 0 <= sr < m
• 0 <= sc < n

Now, let’s see the code of 733. Flood Fill – Leetcode Solution.

Flood Fill – Leetcode Solution

733. Flood Fill – Solution in Java

class Solution {
    
    public void fillIt(int[][] image, int sr, int sc, int color, int trackColor){
        
        if(sr < 0 || sr >= image.length 
           || sc < 0 || sc >= image[0].length) return;
        
        if(trackColor != image[sr][sc]) return;
        
        image[sr][sc] = color;
        
        fillIt(image,sr-1,sc,color,trackColor);
        fillIt(image,sr+1,sc,color,trackColor);
        fillIt(image,sr,sc-1,color,trackColor);
        fillIt(image,sr,sc+1,color,trackColor);
        
    }
    
    public int[][] floodFill(int[][] image, int sr, int sc, int color) {
        if(image[sr][sc] == color) return image;
        fillIt(image,sr,sc,color,image[sr][sc]);
        return image;
    }
}

733. Flood Fill – Solution in C++

class Solution {
public:
    
    void dfs(vector<vector<int>>& image, int i, int j,int val, int newColor)
    {
        if(i<0 || i>=image.size() || j<0 || j>= image[0].size() || image[i][j] == newColor || image[i][j] != val)
        {
            return;
        }
        image[i][j] = newColor;
        dfs(image,i-1,j,val,newColor);
        dfs(image,i+1,j,val,newColor);
        dfs(image,i,j-1,val,newColor);
        dfs(image,i,j+1,val,newColor);
    }
    
    vector<vector<int>> floodFill(vector<vector<int>>& image, int sr, int sc, int newColor)
    {
        int val = image[sr][sc];
        dfs(image,sr,sc,val,newColor);
        return image;
    }
};

733. Flood Fill – Solution in Python

class Solution(object):
    def floodFill(self, image, sr, sc, newColor):
        rows, cols, orig_color = len(image), len(image[0]), image[sr][sc]
        def traverse(row, col):
            if (not (0 <= row < rows and 0 <= col < cols)) or image[row][col] != orig_color:
                return
            image[row][col] = newColor
            [traverse(row + x, col + y) for (x, y) in ((0, 1), (1, 0), (0, -1), (-1, 0))]
        if orig_color != newColor:
            traverse(sr, sc)
        return image

Note: This problem 733. Flood Fill is generated by Leetcode but the solution is provided by CodingBroz. This tutorial is only for Educational and Learning purpose.