[LeetCode] Ugly Number

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.

根据丑数的定义，如果一个数能被2整除，我们把它连续除以2；如果能被3整除，就连续除以3，如果能被5整除，就连续除以5。如果最后我们得到的是1，那么这个数就是丑数，否则不是。注意：需要提前判断0是否是丑数，否则会造成死循环。

class Solution {
public:
    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) ? true : false;
    }
};
// 3 ms