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;
}
}
201. Bitwise AND of Numbers Range
原文：http://www.cnblogs.com/shini/p/4433776.html