刷一题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.

Credits:

Special thanks to @jianchao.li.fighter for adding this problem and creating all test cases.

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