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?
最大的int 型3的幂是1162261467
所以只要1162261467%3==0就是3的幂
class Solution { public: bool isPowerOfThree(int n) { if(n<=0)return false; return 1162261467%n==0; } };
原文：http://www.cnblogs.com/csudanli/p/5324732.html