算法

(DFS) $O(n*m)$

DFS，从起点开始枚举4个方向并填充颜色

C++ 代码

class Solution {
public:
    vector<vector<int>> floodFill(vector<vector<int>>& image, int sr, int sc, int newColor) {
        if (image[sr][sc] == newColor) {
            return image;
        }

        fill(image, sr, sc, image[sr][sc], newColor);

        return image;
    }

    void fill(vector<vector<int>> &image, int sr, int sc, int color, int newColor) {
        if (sr < 0 || sr >= image.size() || sc < 0 || sc >= image[0].size() || image[sr][sc] != color) {
            return;
        }

        image[sr][sc] = newColor;

        fill(image, sr + 1, sc, color, newColor);
        fill(image, sr - 1, sc, color, newColor);
        fill(image, sr, sc + 1, color, newColor);
        fill(image, sr, sc - 1, color, newColor);
    }
};