leetcode——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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class Solution {
public:
    bool isPowerOfThree(int n) {
        double result =  log10(n) / log10(3);
        return (result-int(result)==0)?true:false;
    }
};