leetcode 201. Bitwise AND of Numbers Range

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.

求公共的2进制前缀。

5 - 0101  

7 - 0111

5到7之间的数公共的位就是 0100 -> 4

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