LeetCode之326 Power of Three

原题：

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?

AC后的代码（注意，该代码只对素数有用）：

class Solution {public:    bool isPowerOfThree(int n) {        //some int =3^k;        //k=log3(some max int)        if(n<=0) return false;        const int maxint =0x7fffffff;        int k=log(maxint)/log(3);                int somgbig3=pow(3,k);        return (somgbig3%n==0);    }};