263. Ugly Number

1. 问题描述

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.
Tags: Math
Similar Problems: (E) Happy Number (E) Count Primes (M) Ugly Number II

2. 解题思路

3. 代码

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

4. 反思