-- coding:utf-8 --

class GrayCode: def getGray(self, n): # write code here

if n==1:

tmp=['0','1']

else:

tmp=['0'+i for i in self.getGray(n-1)]+['1'+i for i in self.getGray(n-1)[::-1]]

return tmp

    tmp=['0','1']
    for i in range(1,n):
        left=['0'+_ for _ in tmp]
        right=['1'+_ for _ in tmp[::-1]]
        tmp=left+right
    return tmp