【Leetcode】：326. Power of Three 问题 in JAVA

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.

题目要求计算一个数字是否为丑数，对于丑数的定义：如果一个数的质因数只含2,3,5，那么就称为丑数，1是第一个丑数

这是一道数学类型的题目，关键在于如何计算num的质因数是否只含2,3,5

计算过程：如果num能整除5，就一直整除5，如果能整除3就一直整除3,接下来2也一样，如果最后的结果为1，那么就是丑数

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