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.

 

 

按位做， 找到第一个n和m不相同的那一位。 那么后来的肯定都是0。(因为是从m到n连续的数字取AND， 后面的肯定有1有0)

1 public class Solution {

2     public int rangeBitwiseAnd(int m, int n) {

3         int result = 0;

4         for(int i = 31; i >= 0 && (((m >> i) & 1) == ((n >> i) & 1)); i --){

5             result |= (((m >> i) & 1) << i);

6         }

7         return result;

8     }

9 }