326. 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?

一刷
题解：居然不懂power的意思。意思是，n是不是3的某次方。
3^20 > Integer.MAX_VALUE, 3^19<Integer.MAX_VALUE
如果(3^19)%n == 0, 表示n的因子中只有3

class Solution {
    public boolean isPowerOfThree(int n) {
        return (n>0 && 1162261467%n == 0);
    }
}