263. Ugly Number

题目：

Write a program to check whether a given number is an ugly number.

Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 6, 8 are ugly while 14 is not ugly since it includes another prime factor 7.

Note that 1 is typically treated as an ugly number.

链接： http://leetcode.com/problems/ugly-number/

3/5/2017

注意题目中写了必须是正数才会是丑数。

public class Solution {
    public boolean isUgly(int num) {
        if (num <= 0) return false;
        while (num % 5 == 0) num /= 5;
        while (num % 3 == 0) num /= 3;
        while (num % 2 == 0) num /= 2;
        
        return num == 1;
    }
}