# 661. Image Smoother 图片平滑器

@TOC

## # 题目描述

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].

## # 解题方法

### # 方法一：暴力解决

``````from copy import deepcopy as copy
class Solution(object):
def imageSmoother(self, M):
"""
:type M: List[List[int]]
:rtype: List[List[int]]
"""
if not M or not M[0]:
return M
rows = len(M)
cols = len(M[0])
isValid = lambda i,j: i >=0 and i < rows and j >= 0 and j < cols
row, col = 0, 0
for row in xrange(rows):
for col in xrange(cols):
_sum, count = 0, 0
for i in xrange(-1, 2):
for j in xrange(-1, 2):
if isValid(row + i, col + j):
_sum += M[row + i][col + j]
count += 1