剑指面试题29-顺时针打印矩阵 python

题目：输入一个矩阵，按照从外向里以顺时针的顺序依次打印出每一个数字，例如，如果输入如下4 X 4矩阵

则依次打印出数字1,2,3,4,8,12,16,15,14,13,9,5,6,7,11,10.

# -*- coding:utf-8 -*-
class Solution:
# matrix类型为二维列表，需要返回列表
def printMatrix(self, matrix):
# write code here
if not matrix:
return None
rows = len(matrix)
cols = len(matrix[0])
start = 0
result = []
while rows > 2*start and cols > 2*start:
endx = rows-1-start
endy = cols-1-start
for i in range(start,endy+1):
result.append(matrix[start][i])
if start < endx:
for i in range(start+1,endx+1):
result.append(matrix[i][endy])
if start < endx and start < endy:
for i in range(endy-1,start-1,-1):
result.append(matrix[endx][i])
if start < endx-1 and start < endy:
for i in range(endx-1,start,-1):
result.append(matrix[i][start])

start += 1
return result