# 661. Image Smoother

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.

Example 1:

``````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:

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

``````class Solution {
public:
vector<vector<int>> imageSmoother(vector<vector<int>>& M) {
if (M.empty() || M[0].empty()) return {};
int m = M.size(), n = M[0].size();
vector<vector<int>> res = M, dirs{{0,-1},{-1,-1},{-1,0},{-1,1},{0,1},{1,1},{1,0},{1,-1}};
for (int i = 0; i < m; ++i) {
for (int j = 0; j < n; ++j) {
int cnt = M[i][j], all = 1;
for (auto dir : dirs) {
int x = i + dir[0], y = j + dir[1];
if (x < 0 || x >= m || y < 0 || y >= n) continue;
++all;
cnt += M[x][y];
}
res[i][j] = cnt / all;
}
}
return res;
}
};
``````

LeetCode All in One 题目讲解汇总(持续更新中…)

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