#Leetcode# 201. Bitwise AND of Numbers Range

https://leetcode.com/problems/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.

Example 1:

Input: [5,7]
Output: 4

Example 2:

Input: [0,1]
Output: 0

代码：

class Solution {
public:
    int rangeBitwiseAnd(int m, int n) {
        int cnt = 0;
        while(m != n) {
            m /= 2;
            n /= 2;
            cnt ++;
        }
        return (n << cnt);
    }
};

　　找到 $m$ 到 $n$ 之间的左右数字公共的最左边 一直左移（相当于除 $2$）直到 $n$ 和 $m$ 相等 记录下移动的位数然后结果是移回去的数字