263. 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.

Example 1:

Input: 6
Output: true
Explanation: 6 = 2 × 3

Example 2:

Input: 8
Output: true
Explanation: 8 = 2 × 2 × 2

Example 3:

Input: 14
Output: false 
Explanation: 14 is not ugly since it includes another prime factor 7.

Note:

1. 1 is typically treated as an ugly number.

2. Input is within the 32-bit signed integer range: [−231, 231 − 1].

# @param {Integer} num
# @return {Boolean}
def is_ugly(num)
  return false if num == 0
  while num % 2 == 0
    num = num / 2
  end
  while num % 3 == 0
    num = num / 3
  end
  while num % 5 == 0
    num = num / 5
  end
  num == 1
end