Solution326.h

//
// Author: huanglijun 
// Date  : 2019/7/25
// Desc  : 326. Power of Three
//

/*
 * 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?
 */

#ifndef TESTCODE_SOLUTION326_H
#define TESTCODE_SOLUTION326_H

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

    while(n > 3){
        n /= 3;
        if(n%3 != 0) return false;
    }
    return (n == 3);
}

#endif //TESTCODE_SOLUTION326_H