[Leetcode] 693. Binary Number with Alternating Bits

Description:

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.

class Solution {
    public boolean hasAlternatingBits(int n) {
        boolean result = false;
        result = ((n + (n>>1)+ 1) & (n + (n>>1))) == 0 ;
        return result;
    }
}

这里使用的算法是：

如果一个数字n是0与1交替循环的话

那么把n>>1向右移一位得到n'

n+n' 会得到111111  再加1会得到 1000000

最后111111 & 1000000会得到 0000000