题目

bitwise-and-of-numbers-range

算法

* 直接模拟

* mask

3. 代码

* 直接模拟

class Solution {
public:
    int rangeBitwiseAnd(int m, int n) {
        int d = INT_MAX;
        while ((m & d) != (n & d)) {
            d <<= 1;
        }
        return m & d;
    }
};

* mask

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