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.

这题如果按照题意做会超时，用移位的操作很妙，因为是并操作，其实只要最小的数和最大的数从左往右取相同的位即可。遇到不同就退出，因为他们中间肯定有数该为为0。

class Solution {public:    int rangeBitwiseAnd(int m, int n) {        int p = 0;        while(m != n) {        m = m >> 1;        n = n >> 1;        p++;        }        return m << p;    }   };