An image is represented by an m x n integer grid image where image[i][j] represents the pixel value of the image.
You are also given three integers sr, sc, and color. You should perform a flood fill on the image starting from the pixel image[sr][sc].
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), and so on. Replace the color of all of the aforementioned pixels with color.
Return the modified image after performing the flood fill.
Example 1:
Input: image = [[1,1,1],[1,1,0],[1,0,1]], sr = 1, sc = 1, color = 2 Output: [[2,2,2],[2,2,0],[2,0,1]] Explanation: From the center of the image with position (sr, sc) = (1, 1) (i.e., the red pixel), all pixels connected by a path of the same color as the starting pixel (i.e., the blue pixels) 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.
Example 2:
Input: image = [[0,0,0],[0,0,0]], sr = 0, sc = 0, color = 0 Output: [[0,0,0],[0,0,0]] Explanation: The starting pixel is already colored 0, so no changes are made to the image.
Constraints:
m == image.lengthn == image[i].length1 <= m, n <= 500 <= image[i][j], color < 2160 <= sr < m0 <= sc < n
DFS or BFS.
Flood fill, also called seed fill, is a flooding algorithm that determines and alters the area connected to a given node in a multi-dimensional array with some matching attribute. It is used in the "bucket" fill tool of paint programs to fill connected, similarly-colored areas with a different color.
DFS:
class Solution:
def floodFill(
self, image: List[List[int]], sr: int, sc: int, newColor: int
) -> List[List[int]]:
def dfs(i, j, oc, nc):
if (
i < 0
or i >= len(image)
or j < 0
or j >= len(image[0])
or image[i][j] != oc
or image[i][j] == nc
):
return
image[i][j] = nc
for x, y in [[0, 1], [0, -1], [1, 0], [-1, 0]]:
dfs(i + x, j + y, oc, nc)
dfs(sr, sc, image[sr][sc], newColor)
return imageBFS:
class Solution:
def floodFill(self, image: List[List[int]], sr: int, sc: int, newColor: int) -> List[List[int]]:
if image[sr][sc] == newColor:
return image
q = deque([(sr, sc)])
oc = image[sr][sc]
image[sr][sc] = newColor
while q:
i, j = q.popleft()
for a, b in [[0, -1], [0, 1], [1, 0], [-1, 0]]:
x, y = i + a, j + b
if 0 <= x < len(image) and 0 <= y < len(image[0]) and image[x][y] == oc:
q.append((x, y))
image[x][y] = newColor
return imageDFS:
class Solution {
private int[][] dirs = new int[][]{{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
public int[][] floodFill(int[][] image, int sr, int sc, int newColor) {
dfs(image, sr, sc, image[sr][sc], newColor);
return image;
}
private void dfs(int[][] image, int i, int j, int oc, int nc) {
if (i < 0 || i >= image.length || j < 0 || j >= image[0].length || image[i][j] != oc || image[i][j] == nc) {
return;
}
image[i][j] = nc;
for (int[] dir : dirs) {
dfs(image, i + dir[0], j + dir[1], oc, nc);
}
}
}BFS:
class Solution {
public int[][] floodFill(int[][] image, int sr, int sc, int newColor) {
if (image[sr][sc] == newColor) {
return image;
}
Deque<int[]> q = new ArrayDeque<>();
q.offer(new int[] {sr, sc});
int oc = image[sr][sc];
image[sr][sc] = newColor;
int[] dirs = {-1, 0, 1, 0, -1};
while (!q.isEmpty()) {
int[] p = q.poll();
int i = p[0], j = p[1];
for (int k = 0; k < 4; ++k) {
int x = i + dirs[k], y = j + dirs[k + 1];
if (x >= 0 && x < image.length && y >= 0 && y < image[0].length
&& image[x][y] == oc) {
q.offer(new int[] {x, y});
image[x][y] = newColor;
}
}
}
return image;
}
}DFS:
class Solution {
public:
vector<vector<int>> dirs = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
vector<vector<int>> floodFill(vector<vector<int>>& image, int sr, int sc, int newColor) {
dfs(image, sr, sc, image[sr][sc], newColor);
return image;
}
void dfs(vector<vector<int>>& image, int i, int j, int oc, int nc) {
if (i < 0 || i >= image.size() || j < 0 || j >= image[0].size() || image[i][j] != oc || image[i][j] == nc) return;
image[i][j] = nc;
for (auto& dir : dirs) dfs(image, i + dir[0], j + dir[1], oc, nc);
}
};BFS:
class Solution {
public:
vector<vector<int>> floodFill(vector<vector<int>>& image, int sr, int sc, int newColor) {
if (image[sr][sc] == newColor) return image;
int oc = image[sr][sc];
image[sr][sc] = newColor;
queue<pair<int, int>> q;
q.push({sr, sc});
vector<int> dirs = {-1, 0, 1, 0, -1};
while (!q.empty())
{
auto p = q.front();
q.pop();
for (int k = 0; k < 4; ++k)
{
int x = p.first + dirs[k];
int y = p.second + dirs[k + 1];
if (x >= 0 && x < image.size() && y >= 0 && y < image[0].size() && image[x][y] == oc)
{
q.push({x, y});
image[x][y] = newColor;
}
}
}
return image;
}
};DFS:
func floodFill(image [][]int, sr int, sc int, newColor int) [][]int {
dfs(image, sr, sc, image[sr][sc], newColor)
return image
}
func dfs(image [][]int, i, j, oc, nc int) {
if i < 0 || i >= len(image) || j < 0 || j >= len(image[0]) || image[i][j] != oc || image[i][j] == nc {
return
}
image[i][j] = nc
dirs := [4][2]int{{0, -1}, {0, 1}, {1, 0}, {-1, 0}}
for _, dir := range dirs {
dfs(image, i+dir[0], j+dir[1], oc, nc)
}
}BFS:
func floodFill(image [][]int, sr int, sc int, newColor int) [][]int {
if image[sr][sc] == newColor {
return image
}
oc := image[sr][sc]
q := [][]int{[]int{sr, sc}}
image[sr][sc] = newColor
dirs := []int{-1, 0, 1, 0, -1}
for len(q) > 0 {
p := q[0]
q = q[1:]
for k := 0; k < 4; k++ {
x, y := p[0]+dirs[k], p[1]+dirs[k+1]
if x >= 0 && x < len(image) && y >= 0 && y < len(image[0]) && image[x][y] == oc {
q = append(q, []int{x, y})
image[x][y] = newColor
}
}
}
return image
}function floodFill(
image: number[][],
sr: number,
sc: number,
newColor: number,
): number[][] {
const m = image.length;
const n = image[0].length;
const target = image[sr][sc];
const dfs = (i: number, j: number) => {
if (
i < 0 ||
i === m ||
j < 0 ||
j === n ||
image[i][j] !== target ||
image[i][j] === newColor
) {
return;
}
image[i][j] = newColor;
dfs(i + 1, j);
dfs(i - 1, j);
dfs(i, j + 1);
dfs(i, j - 1);
};
dfs(sr, sc);
return image;
}impl Solution {
fn dfs(image: &mut Vec<Vec<i32>>, sr: i32, sc: i32, new_color: i32, target: i32) {
if sr < 0 || sr == image.len() as i32 || sc < 0 || sc == image[0].len() as i32 {
return;
}
let sr = sr as usize;
let sc = sc as usize;
if sr < 0 || image[sr][sc] == new_color || image[sr][sc] != target {
return;
}
image[sr][sc] = new_color;
let sr = sr as i32;
let sc = sc as i32;
Self::dfs(image, sr + 1, sc, new_color, target);
Self::dfs(image, sr - 1, sc, new_color, target);
Self::dfs(image, sr, sc + 1, new_color, target);
Self::dfs(image, sr, sc - 1, new_color, target);
}
pub fn flood_fill(image: Vec<Vec<i32>>, sr: i32, sc: i32, new_color: i32) -> Vec<Vec<i32>> {
let target = image[sr as usize][sc as usize];
Self::dfs(&mut image, sr, sc, new_color, target);
image
}
}