Solution.py

"""
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:
The value in the given matrix is in the range of [0, 255].
The length and width of the given matrix are in the range of [1, 150].
"""
class Solution(object):
    def imageSmoother(self, M):
        """
        :type M: List[List[int]]
        :rtype: List[List[int]]
        """
        r = []
        for i, row in enumerate(M):
            tr = []
            for j, cell in enumerate(row):
                num, s = 0, 0
                for xd in xrange(-1, 2, 1):
                    for yd in xrange(-1, 2, 1):
                        if i + xd < 0:
                            continue
                        if j + yd < 0:
                            continue
                        try:
                            s += M[i + xd][j + yd]
                            num += 1
                        except IndexError:
                            pass
                tr.append(s / num)
            r.append(tr)
        return r