leetcode------Bitwise AND of Numbers Range

标题：	Bitwise AND of Numbers Range
通过率：	25.7%
难度：	中等

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.

就是将区间内的所有数字按位与的结果，如果按照每个数字的去与，那么是超时的，直接贴出代码把。。这个只能生办硬套：

class Solution:
    # @param m, an integer
    # @param n, an integer
    # @return an integer
    def rangeBitwiseAnd(self, m, n):
        offset=0
        while m !=n :
            m>>=1
            n>>=1
            offset+=1
        return m<<offset