733. Image rendering

The difficulty is simple 278
There is a picture in two-dimensional integer array , Each integer represents the pixel value size of the picture , Values in 0 To 65535 Between .
Give you a coordinate (sr, sc) Represents the pixel value at the beginning of image rendering （ That's ok , Column ） And a new color value newColor, Let you re color this image .
In order to finish the coloring work , From the initial coordinates , Record the connected pixel points with the same pixel value in the upper, lower, left and right four directions of the initial coordinate , Then record the qualified pixel points in these four directions and the connected pixel points with the same pixel values and initial coordinates in their corresponding four directions ,……, Repeat the process . Change the color value of all recorded pixels to the new color value .
Finally, return to the color rendered image .

 Example  1:
 Input : 
image = [[1,1,1],[1,1,0],[1,0,1]]
sr = 1, sc = 1, newColor = 2
 Output : [[2,2,2],[2,2,0],[2,0,1]]
 analysis : 
 In the middle of the image ,( coordinate (sr,sc)=(1,1)),
 The color of all the eligible pixels on the path is changed to 2.
 Be careful , The lower right pixel is not changed to 2,
 Because it is not a pixel point connected to the initial point in four directions .

Be careful :

• image and image[0] The length of is in the range [1, 50] Inside .
• The initial point given will satisfy 0 <= sr < image.length and 0 <= sc < image[0].length.
• image[i][j] and newColor The color value is in the range [0, 65535] Inside .

Ideas

• A special case ： When newcolor==oldcolor, Go straight back to

Code

class Solution {
    
public:
    int oldColor;
    void dfs(vector<vector<int>>& image, int sr, int sc, int newColor){
    
        int n,m;
        n=image.size();
        m=image[0].size();
        if(image[sr][sc]!=oldColor) return;
		// Make a mark ： Has arrived 
        image[sr][sc]=newColor;
        // Continue searching in four directions 
        if(sr+1<n)  dfs(image,sr+1,sc,newColor);
        if(sr-1>=0)   dfs(image,sr-1,sc,newColor);
        if(sc+1<m)    dfs(image,sr,sc+1,newColor);
        if(sc-1>=0)   dfs(image,sr,sc-1,newColor);
    }
    vector<vector<int>> floodFill(vector<vector<int>>& image, int sr, int sc, int newColor) {
    
        oldColor=image[sr][sc];
        if(newColor==oldColor)  return image;

        dfs(image,sr,sc,newColor);
        return image;
    }
};