693. Binary Number with Alternating Bits

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.


判断一个数的二进制中，01是否是交替出现的

C++（3ms）：

class Solution {
public:
    bool hasAlternatingBits(int n) {
        int t1 , t2 ;
        t1 = n%2 ;
        n/=2 ;
        while(n){
          t2 = n%2 ;
          n/=2 ;
          if (t2 == t1)
              return false ;
          t1 = t2 ;
        }
        return true ;
    }
};

C++(3ms):

class Solution {
public:
    bool hasAlternatingBits(int n) {
        int d = n&1 ;
        while((n&1) == d){
            d = 1-d ;
            n >>= 1 ;
        }
        return n == 0 ;
    }
};

java(14ms):

class Solution {
    public boolean hasAlternatingBits(int n) {
        int d = n&1 ;
        while((n&1) == d){
            d = 1-d ;
            n >>= 1 ;
        }
        return n == 0 ;
    }
}