LeetCode/C++/326.cpp

#include <iostream>
#include <cstdint>
#include <cmath>

class Solution {
public:
    bool isPowerOfThree(int n) {
        if ( n <= 0 ) { return false; }
        if ( n == 1 ) { return true; }
        for ( int i = 1; i < n; ++i ) {
            long val = pow(3, i);
            if ( val == n ) { return true; }
            if ( val > n ) { return false; }
        }
        return false;
    }
};

void r(int n, bool exp) {
    std::cout << "Solution().isPowerOfThree(" << n << ") = ";
    std::cout << Solution().isPowerOfThree(n);
    std::cout << " | exp: " << exp << "\n";
};

int main(void) {
    r(27, true);
    r(9, false);
    r(0, false);
    r(-1, false);

    return 0;
}