693.binary-number-with-alternating-bits

Statement

简体中文English

Metadata

• Link: 交替位二进制数
• Difficulty: Easy
• Tag: 位运算

给定一个正整数，检查它的二进制表示是否总是 0、1 交替出现：换句话说，就是二进制表示中相邻两位的数字永不相同。

 

示例 1：

输入：n = 5
输出：true
解释：5 的二进制表示是：101

示例 2：

输入：n = 7
输出：false
解释：7 的二进制表示是：111.

示例 3：

输入：n = 11
输出：false
解释：11 的二进制表示是：1011.

 

提示：

• 1 <= n <= 231 - 1

Metadata

• Link: Binary Number with Alternating Bits
• Difficulty: Easy
• Tag: Bit Manipulation

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

 

Example 1:

Input: n = 5
Output: true
Explanation: The binary representation of 5 is: 101

Example 2:

Input: n = 7
Output: false
Explanation: The binary representation of 7 is: 111.

Example 3:

Input: n = 11
Output: false
Explanation: The binary representation of 11 is: 1011.

 

Constraints:

• 1 <= n <= 231 - 1

Solution

Python 3

class Solution:
    def hasAlternatingBits(self, n: int) -> bool:
        a = n ^ (n >> 1)
        return a & (a + 1) == 0

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最后更新: October 11, 2023