# C#LeetCode刷题之#661-图片平滑器（ Image Smoother）

[[1,1,1],
[1,0,1],
[1,1,1]]

[[0, 0, 0],
[0, 0, 0],
[0, 0, 0]]

Given a 2D integer matrix M representing the gray scale of an image, you need to design a smoother to make the gray scale of each cell becomes the average gray scale (rounding down) of all the 8 surrounding cells and itself. If a cell has less than 8 surrounding cells, then use as many as you can.

Input:
[[1,1,1],
[1,0,1],
[1,1,1]]

Output:
[[0, 0, 0],
[0, 0, 0],
[0, 0, 0]]

Explanation:
For the point (0,0), (0,2), (2,0), (2,2): floor(3/4) = floor(0.75) = 0
For the point (0,1), (1,0), (1,2), (2,1): floor(5/6) = floor(0.83333333) = 0
For the point (1,1): floor(8/9) = floor(0.88888889) = 0

Note:

The value in the given matrix is in the range of [0, 255].
The length and width of the given matrix are in the range of [1, 150].

```public class Program {

public static void Main(string[] args) {
int[,] nums = null;

nums = new int[,] { { 1, 1, 1 }, { 1, 0, 1 }, { 1, 1, 1 } };
var res = ImageSmoother(nums);
ShowArray(res);

}

private static void ShowArray(int[,] array) {
foreach(var num in array) {
Console.Write(\$"{num} ");
}
Console.WriteLine();
}

private static int[,] ImageSmoother(int[,] M) {
int[,] result = M.Clone() as int[,];
for(int i = 0; i < M.GetLength(0); i++) {
for(int j = 0; j < M.GetLength(1); j++) {
result[i, j] = ComputerSmoothValue(M, i, j);
}
}
return result;
}

private static int ComputerSmoothValue(int[,] M, int i, int j) {
//以某个数为中心，求9个数的平均值即可
//该题主要考查边界的处理
int count = 0;
int sum = 0;
for(int m = Math.Max(i - 1, 0); m <= Math.Min(i + 1, M.GetLength(0) - 1); m++) {
for(int n = Math.Max(j - 1, 0); n <= Math.Min(j + 1, M.GetLength(1) - 1); n++) {
count++;
sum += M[m, n];
}
}
return sum / count;
}

}```

`0 0 0 0 0 0 0 0 0`

(1)