leetcode201. Bitwise AND of Numbers Range

Given a range [m, n] where 0 <= m <= n <= 2147483647, return the bitwise AND of all numbers in this range, inclusive.
For example, given the range [5, 7], you should return 4.

看m,n的前缀
101 111 ->100
110 111 ->110

class Solution(object):    def rangeBitwiseAnd(self, m, n):        """        :type m: int        :type n: int        :rtype: int        """        count=0        while(m!=n):            m=m>>1            n=n>>1            count=count+1        return m<<count