693. Binary Number with Alternating Bits (easy)

Q:

Given a positive integer, check whether it has alternating bits: namely, if two adjacent bits will always have different values.

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.

Example 3:

Input: 11
Output: False
Explanation:
The binary representation of 11 is: 1011.

Example 4:

Input: 10
Output: True
Explanation:
The binary representation of 10 is: 1010.

A:

记录前一个位置，并且每次对比

class Solution {
public:
    bool hasAlternatingBits(int n) {
        int pre = (n&1)?0:1;
        while(n)
        {
            if(! (pre ^ (n&1)) ) 
            {
                return false;
            }
            pre = 1-pre;
            n = n>>1;
        }
        return true;
    }
};

记录前一个位置，并且每次对比