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.

[思路]

等价于 求 m 与 n 二进制编码中 同为1的前缀.

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