leetcode 201. Bitwise AND of Numbers Range(位运算,dp)

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.

题解：如果m==n，那么答案就是m.

如果m<n，那么二进制最右边一位在最后的结果中肯定是0，那么就可以转化成子问题:

rangeBitwiseAnd(m>>1, n>>1)

 

class Solution {
public:
    int rangeBitwiseAnd(int m, int n) {
        return (n > m) ? (rangeBitwiseAnd(m>>1, n>>1) << 1) : m;
    }
};