Leetcode Ugly Number

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.

最直接的办法就是不停的除以这些质数，如果剩余的数字是1的话就是Ugly number了

Java code:

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

Reference:
http://www.cnblogs.com/grandyang/p/4741934.html