[Leetcode] 263. Ugly Number 解题报告

题目：

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：
判断被2,3,5除尽之后是否等于1即可，太简单了没什么好说的。

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