LeetCode OJ：Ugly Number（丑数）

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.

丑数的计算，分别去除数字中的2，3，5部分，如果数字被整除了那么就是丑数，否则不是，下见代码：

class Solution {
public:
bool isUgly(int num) {
if(num == 0)
return false;
while(num % 2 == 0) num /= 2;//exclude 2 factor
while(num % 3 == 0) num /= 3;//exclude 3 factor
while(num % 5 == 0) num /= 5;//exclude 5 factor
return (num == 1);//is Ugly
}
};

java版本如下所示，方法相同：

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