python:

class Solution:
    def floodFill(self, image, sr, sc, newColor):
        """
        :type image: List[List[int]]
        :type sr: int
        :type sc: int
        :type newColor: int
        :rtype: List[List[int]]
        """
        rows, columns = len(image), len(image[0])
        same = image[sr][sc]
        if newColor is same:
            return image
        def Fill(row, column):
            if 0<=row<rows and 0<=column<columns and image[row][column] == same:
                image[row][column] = newColor
            else:
                return
            Fill(row+1, column)
            Fill(row-1, column)
            Fill(row, column+1)
            Fill(row, column-1)
        Fill(sr, sc)
        return image
        
 

c++:

class Solution {
private:
    int m_num;
    int m_newColor;
    int rows;
    int cols;
public:
    vector<vector<int>> floodFill(vector<vector<int>>& image, int sr, int sc, int newColor) {
        m_num = image[sr][sc];
        if (m_num == newColor)
            return image;
        rows = image.size();
        cols = image[0].size();
        m_newColor = newColor;
        
        fill(sr, sc, image);
        return image;
        
    }
    
    void fill(int row, int col, vector<vector<int>>& image){
        if( row<0 || row>=rows || col<0 || col>=cols || image[row][col]!=m_num)
            return;
        image[row][col] = m_newColor;
        fill(row+1, col, image);
        fill(row-1, col, image);
        fill(row, col+1, image);
        fill(row, col-1, image);
    }
};