[Leetcode] 733. Flood Fill 解题报告

题目：

An 

image

 is represented by a 2-D array of integers, each integer representing the pixel
value of the image (from 0 to 65535).

Given a coordinate 

(sr, sc)

 representing the starting pixel (row and column) of the flood
fill, and a pixel value 

newColor

, "flood fill" the image.

To perform a "flood fill", consider the starting pixel, plus any pixels connected 4-directionally to the starting pixel of the same color as the starting pixel, plus any pixels connected 4-directionally to those pixels (also with the same color as the starting
pixel), and so on. Replace the color of all of the aforementioned pixels with the newColor.

At the end, return the modified 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]]
Explanation:
From the center of the image (with position (sr, sc) = (1, 1)), all pixels connected
by a path of the same color as the starting pixel are colored with the new color.
Note the bottom corner is not colored 2, because it is not 4-directionally connected
to the starting pixel.

Note:

The length of 

image

 and 

image[0]

 will
be in the range 

[1, 50]

.
The given starting pixel will satisfy 

0 <= sr < image.length

 and 

0
<= sc < image[0].length

.
The value of each color in 

image[i][j]

 and 

newColor

 will
be an integer in 

[0, 65535]

.
思路：

最最最原始的DFS题目^_^。

代码：

class Solution {
public:
vector<vecto
ade8
r<int>> floodFill(vector<vector<int>>& image, int sr, int sc, int newColor) {
vector<vector<int>> new_image(image);
int oldColor = image[sr][sc];
if (oldColor != newColor) {
DFS(new_image, sr, sc, oldColor, newColor);
}
return new_image;
}
private:
void DFS(vector<vector<int>> &new_image, int r, int c, int old_color, int new_color) {
int row_num = new_image.size(), col_num = new_image[0].size();
if (r < 0 || r >= row_num || c < 0 || c >= col_num || new_image[r][c] != old_color) {
return;
}
new_image[r][c] = new_color;
DFS(new_image, r - 1, c, old_color, new_color);
DFS(new_image, r + 1, c, old_color, new_color);
DFS(new_image, r, c - 1, old_color, new_color);
DFS(new_image, r, c + 1, old_color, new_color);
}
};