0733. Flood Fill

https://leetcode.com/problems/flood-fill/description/

Time: O(m*n)
Space: O(m*n)

class Solution {
    public int[][] floodFill(int[][] image, int sr, int sc, int color) {
        int old = image[sr][sc];
        if (old != color) {
            dfs(image, sr, sc, old, color);
        }
        return image;
    }

    private void dfs(int[][] image, int row, int col, int old, int color) {
        if (image[row][col] == old) {
            image[row][col] = color;
            if (row >= 1) {
                dfs(image, row - 1, col, old, color);
            }
            if (row < image.length - 1) {
                dfs(image, row + 1, col, old, color);
            }
            if (col >= 1) {
                dfs(image, row, col - 1, old, color);
            }
            if (col < image[0].length - 1) {
                dfs(image, row, col + 1, old, color);
            }
        }
    }
}