326. Power of Three

Problem:

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

Example 1:

Input: 27
Output: true

Example 2:

Input: 0
Output: false

Example 3:

Input: 9
Output: true

Example 4:

Input: 45
Output: false

Follow up:
Could you do it without using any loop / recursion?

思路：

Solution (C++):

bool isPowerOfThree(int n) {
    if (n <= 0)  return false;
    while (n%3 == 0)  n /= 3;
    if (n == 1)  return true;
    return false;
}

性能：

Runtime: 40 ms  Memory Usage: 5.8 MB

思路：

Solution (C++):

性能：

Runtime: ms  Memory Usage: MB