326. Power of Three

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

Follow up:

Could you do it without using any loop / recursion?

Credits:

Special thanks to
@dietpepsi for adding this problem and creating all test cases.

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说不用递归或循环，没有想到解法。

代码class Solution {
public:
bool isPowerOfThree(int n) {
while(n>=3)
{
if(n%3!=0)
return false;
n=n/3;
}
return n==1;
}
};