231. Power of Two

Problem:

Given an integer, write a function to determine if it is a power of two.

Example 1:

Input: 1
Output: true 
Explanation: 20 = 1

Example 2:

Input: 16
Output: true
Explanation: 24 = 16

Example 3:
``
Input: 218
Output: false

**思路**：



**Solution (C++)**:

```c
bool isPowerOfTwo(int n) {
    if (n <= 0)  return false;
    if (n == 1)  return true;
    while (n > 2) {
        if (n%2 != 0)  return false;
        n /= 2;
    }
    return true;
}

性能：

Runtime: 0 ms  Memory Usage: 6.1 MB

思路：

Solution (C++):

性能：

Runtime: ms  Memory Usage: MB