Binary Number with Alternating Bits

Given a positive integer, check whether it has alternating bits or not.
Example 1:
Input: 5
Output: True
Explanation:
The binary representation of 5 is: 101
Example 2:
Input: 7
Output: False
Explanation:
The binary representation of 7 is: 111

//法一：
class Solution {
public:
    bool hasAlternatingBits(int n)
    {//5->101
        int last = n & 1;//按位与取最后一个
        n >>= 1;
        while (n != 0)
        {
            if (last == (n & 1))//最后一个和次个比较
            {
                return false;
            }
            else
            {
                last = n & 1;
            }
            n >>= 1;
        }
        return true;

    }
};

//法二：
class Solution {
public:
    bool hasAlternatingBits(int n)
    {
        int d = n & 1;
        while ((n & 1) == d) //若d=1
        {
            d = 1 - d;//则d=0
            n >>= 1;//右移，取次个，比较次个是否等于0
        }
        return n == 0;
    }
};