LeetCode:Power of Three

Posted on In Disqus:

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

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    class Solution {
    public:
        bool isPowerOfThree(int n) {
            double dtmp = log10(n) / log10(3);
            return int(dtmp) - dtmp == 0;
        }
    };