0%

LeetCode: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?

解题思路:

  1. 用数学公式$\frac{log_{10}n}{log_{10}3}$为整数
  2. 更多参考:http://blog.csdn.net/ebowtang/article/details/50485622

    code

    1
    2
    3
    4
    5
    6
    7
    class Solution {
    public:
    bool isPowerOfThree(int n) {
    double dtmp = log10(n) / log10(3);
    return int(dtmp) - dtmp == 0;
    }
    };