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.

 

 

按位作， 找到第一個n和m不相同的那一位。 那麼後來的確定都是0。(由於是從m到n連續的數字取AND， 後面的確定有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 }