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?
public class Solution { public boolean isPowerOfThree(int n) { return n == 0 ? false : n == Math.pow(3, Math.round(Math.log(n) / Math.log(3))); } }
reference: https://leetcode.com/discuss/78481/java-one-line-solution-using-math-knowledge
原文：http://www.cnblogs.com/hygeia/p/5123221.html