263. Ugly Number(数字类型题目)

problem：

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.

Example 1:

Input: 6
Output: true
Explanation: 6 = 2 × 3

Example 2:

Input: 8
Output: true
Explanation: 8 = 2 × 2 × 2

Example 3:

Input: 14
Output: false
Explanation: 14 is not ugly since it includes another prime factor 7.

tip:

ugly数字的质因数只有2,3,5.

solution:

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