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.

 

这个题的主要思路就是将这个数中的关于2,3,5的素数因子除尽，才看看剩下的因子是不是等于1。如果等于1说明没有其他素数因子，则说明该数是ugly的。否则就不是

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;
    }
};