0733. Flood Fill

# 733. Flood Fill#

## 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]`.

## 题目大意 #

• image 和 image[0] 的长度在范围 [1, 50] 内。
• 给出的初始点将满足 0 <= sr < image.length 和 0 <= sc < image[0].length。
• image[i][j] 和 newColor 表示的颜色值在范围 [0, 65535]内。

## 解题思路 #

• 给出一个二维的图片点阵，每个点阵都有一个数字。给出一个起点坐标，要求从这个起点坐标开始，把所有与这个起点连通的点都染色成 newColor。
• 这一题是标准的 Flood Fill 算法。可以用 DFS 也可以用 BFS 。

## 代码 #

``````
package leetcode

func floodFill(image [][]int, sr int, sc int, newColor int) [][]int {
color := image[sr][sc]
if newColor == color {
return image
}
dfs733(image, sr, sc, newColor)
return image
}

func dfs733(image [][]int, x, y int, newColor int) {
if image[x][y] == newColor {
return
}
oldColor := image[x][y]
image[x][y] = newColor
for i := 0; i < 4; i++ {
if (x+dir[i][0] >= 0 && x+dir[i][0] < len(image)) && (y+dir[i][1] >= 0 && y+dir[i][1] < len(image[0])) && image[x+dir[i][0]][y+dir[i][1]] == oldColor {
dfs733(image, x+dir[i][0], y+dir[i][1], newColor)
}
}
}

``````

Apr 8, 2023