142. O(1) Check Power of 2【easy】

142. O(1) Check Power of 2【easy】

Using O(1) time to check whether an integer n is a power of 2.

Have you met this question in a real interview?

Yes

Example

For n=4, return true;

For n=5, return false;

Challenge

O(1) time

解法一：

 class Solution {
 public:
     /*
      * @param n: An integer
      * @return: True or false
      */
     bool checkPowerOf2(int n) {
         if (n >  && (n & n - ) == ) {
             return true;
         }

         return false;
     }
 };