https://leetcode-cn.com/problems/reverse-bits/
class Solution:
# @param n, an integer
# @return an integer
def reverseBits(self, n):
#int转成二进制字符串
#除去‘0b’开头后反转
str1 = bin(n)[2:][::-1]
#补0
if len(str1) < 32:
str1 += '0'*(32-len(str1))
#转成二进制int
return(int(str1, 2))