733. image rendering

It can be understood as width traversal of graph
If the colors are the same, exit directly to prevent infinite recursion

class Solution {
public:
class pos
{
	public:
		int x_;
		int y_;
		pos(int x, int y):x_(x),y_(y){}
};

vector<vector<int>> floodFill(vector<vector<int>>& image, int sr, int sc, int color) {
	if(image.empty())
		return image;
	int standard_color = image.at(sr).at(sc);
	if(color == standard_color)
		return image;
	queue<pos>to_use;
	to_use.push(pos(sr,sc));
	image.at(sr).at(sc) = color;
	while(!to_use.empty())
	{
		auto cur_pos = to_use.front();
		to_use.pop();
		if(cur_pos.x_-1 >=0 && image.at(cur_pos.x_-1).at(cur_pos.y_)==standard_color)
		{
			image.at(cur_pos.x_-1).at(cur_pos.y_) = color;
			to_use.push(pos(cur_pos.x_-1, cur_pos.y_));
		}

		if(cur_pos.x_+1 <(int)image.size() && image.at(cur_pos.x_+1).at(cur_pos.y_)==standard_color)
		{
			image.at(cur_pos.x_+1).at(cur_pos.y_) = color;
			to_use.push(pos(cur_pos.x_+1, cur_pos.y_));
		}
		if(cur_pos.y_-1 >=0 && image.at(cur_pos.x_).at(cur_pos.y_-1)==standard_color)
		{
			image.at(cur_pos.x_).at(cur_pos.y_-1) = color;
			to_use.push(pos(cur_pos.x_, cur_pos.y_-1));
		}
		if(cur_pos.y_+1<(int)image[0].size() && image.at(cur_pos.x_).at(cur_pos.y_+1)==standard_color)
		{
			image.at(cur_pos.x_).at(cur_pos.y_+1) = color;
			to_use.push(pos(cur_pos.x_, cur_pos.y_+1));
		}
	}
	return image;
}



};