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.
① n&(n⑴),可以去除n的最低位的1。
② 从n1直与到m,可以去掉的1就是n和m的右端不相等的部份的1。
例如对以下m和n:
110100111101