661. 图片平滑器

class Solution {
    public int[][] imageSmoother(int[][] img) {
        int n = img.length;
        int m = img[0].length;
        int[][] res = new int[n][m];
        for(int i = 0;i<n;i++){
            for(int j = 0;j<m;j++){
                int count = 0;
                for(int in = i-1;in<=i+1;in++){
                    for(int jm = j-1;jm<=j+1;jm++){
                        if(in>=0&&in<n&&jm>=0&&jm<m){
                            res[i][j] += img[in][jm]; 
                            count++;
                        }
                    }
                }
                res[i][j] /= count; 
            }
        }
    return res;
    }
}