Leetcode 263. 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.

判断一个数的素数因子是否只有2,3,5.

模拟一下就可以了。

class Solution {
public:
    bool isUgly(int num) 
    {
        if (num <= 0) return false;
        int divisors[3] = {2, 3, 5};
        for(int d : divisors) while (num % d == 0) num /= d;
        return num == 1;
    }
};