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.

Solution:

  1. public class Solution {
  2.   public boolean isUgly(int num) {
  3.     if (num == 0) 
  4.       return false;
  6.     while (num != 1) {
  7.       if (num % 2 == 0) {
  8.         num /= 2;
  9.       } else if (num % 3 == 0) {
  10.         num /= 3;
  11.       } else if (num % 5 == 0) {
  12.         num /= 5;
  13.       } else {
  14.         return false;
  15.       }
  16.     }
  18.     return true;
  19.   }
  20. }