[LintCode] Ugly Number 丑陋数

class Solution {
public:
    /**
     * @param num an integer
     * @return true if num is an ugly number or false
     */
    bool isUgly(int num) {
        while (num > 1) {
            if (num % 2 == 0) num /= 2;
            else if (num % 3 == 0) num /= 3;
            else if (num % 5 == 0) num /= 5;
            else return false;
        }
        return num == 1;
    }
};

class Solution {
public:
    /**
     * @param num an integer
     * @return true if num is an ugly number or false
     */
    bool isUgly(int num) {
        if (num <= 0) return false;
        while (num % 2 == 0) num /= 2;
        while (num % 3 == 0) num /= 3;
        while (num % 5 == 0) num /= 5;
        return num == 1;
    }
};