LeetCode | 231. Power of Two

 

题目：

Given an integer n, return true if it is a power of two. Otherwise, return false.

An integer n is a power of two, if there exists an integer x such that n == 2x.

 

Example 1:

Input: n = 1
Output: true
Explanation: 20 = 1

Example 2:

Input: n = 16
Output: true
Explanation: 24 = 16

Example 3:

Input: n = 3
Output: false

Example 4:

Input: n = 4
Output: true

Example 5:

Input: n = 5
Output: false

 

Constraints:

• -231 <= n <= 231 - 1

 

代码：

class Solution {
public:
    bool isPowerOfTwo(int n) {
        int base = log(n*1.0) / log(2.0);
        if(pow(2, double(base)) == n && n)
            return true;
        else
            return false;
    }
};

 

代码虽然简短，但是效率很低啊~2333333