201. 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.

StackOverflow：http://math.stackexchange.com/questions/1073532/how-to-find-bitwise-and-of-all-numbers-for-a-given-range

寻找最高位m和n都是1的值既是所要的。但是同时所有低位值都要被清零。

public class Solution {
　　public int rangeBitwiseAnd(int m, int n) {
　　　　int a = m^n;
　　　　int s = a >> 1;
　　　　while (s != 0) {
　　　　　　a |= s;
　　　　　　s >>= 1;
　　　　}
　　　　return m&n&~a;
　　}
}