leetcode 661 Image Smoother

class Solution {    public int[][] imageSmoother(int[][] M) {        if (M == null || M.length == 0) return new int[0][0];        int x=M.length;        int y=M[0].length;        int [][] result=new int[x][y];        int [][] dir ={{0,0},{0,1},{1,0},{1,1},{0,-1},{-1,0},{-1,-1},{-1,1},{1,-1}};        for(int i=0;i<x;i++){            for(int j=0;j<y;j++){                int sum=0,count=0;                for(int[] k:dir){                    if(i+k[0]>=0 && i+k[0]<x && j+k[1]>=0 && j+k[1]<y){                        sum+=M[i+k[0]][j+k[1]];                        count++;                    }                    result[i][j]=sum/count;                }            }               }        return result;    }}