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?

判断整数是不是3的幂数

 

bool isPowerOfThree(int n) {
    // 1162261467 is 3^19,  3^20 is bigger than int  
    return ( n>0 &&  1162261467%n==0);
}