LeetCode:Ugly Number

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.

思路：

注意考虑循环退出条件以及边界条件。

代码：

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