算法1

注意边界即可。

时间复杂度 $O(mn)$

C++ 代码

class Solution {
public:
    int getd(vector<vector<int>>& M,int x,int y){
        int x1 = x - 1 < 0 ? 0:x-1;
        int y1 = y - 1 < 0 ? 0:y-1;
        int x2 = x + 1 > M.size() - 1 ? M.size() - 1:x + 1;
        int y2 = y + 1 > M[0].size() - 1 ? M[0].size() - 1 : y + 1;
        int n = (x2 - x1 + 1)*(y2 - y1 + 1);
        int sum = 0;
        for(int i = x1 ;i <= x2;++i){
            for(int j = y1; j <= y2;++j){
                sum += M[i][j];
            }
        }
        return sum/n;
    }
    vector<vector<int>> imageSmoother(vector<vector<int>>& M) {
        vector<vector<int>>ans;
        for(int i =0;i < M.size();++i){
            vector<int>t;
            for(int j =0;j < M[0].size();++j){
                int ts = getd(M,i,j);
                t.push_back(ts);
            }
            ans.push_back(t);
        }
        return ans;
    }
};

```