# 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 is typically treated as an ugly number.
- Input is within the 32-bit signed integer range: [−2^31, 2^31 − 1].
# Solution
Approach 1: Check if the number can only be divided by 2, 3, 5.
# Code (Python)
Approach 1:
def isUgly(self, num: int) -> bool:
if num <= 0:
return False
uglies = [2, 3, 5]
for ugly in uglies:
while num % ugly == 0:
num = num / ugly
return num == 1
# Code (C++)
Approach 1:
class Solution {
public:
bool isUgly(int num) {
if (num == 0) return false;
while (num % 2 == 0) num = num / 2;
while (num % 3 == 0) num = num / 3;
while (num % 5 == 0) num = num / 5;
return num == 1;
}
};